Artigos de revistas: "Maltose"

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Visnapuu, Triinu, Aivar Meldre, Kristina Põšnograjeva, Katrin Viigand, Karin Ernits e Tiina Alamäe. "Characterization of a Maltase from an Early-Diverged Non-Conventional Yeast Blastobotrys adeninivorans". International Journal of Molecular Sciences 21, n.º 1 (31 de dezembro de 2019): 297. http://dx.doi.org/10.3390/ijms21010297.

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Genome of an early-diverged yeast Blastobotrys (Arxula) adeninivorans (Ba) encodes 88 glycoside hydrolases (GHs) including two α-glucosidases of GH13 family. One of those, the rna_ARAD1D20130g-encoded protein (BaAG2; 581 aa) was overexpressed in Escherichia coli, purified and characterized. We showed that maltose, other maltose-like substrates (maltulose, turanose, maltotriose, melezitose, malto-oligosaccharides of DP 4‒7) and sucrose were hydrolyzed by BaAG2, whereas isomaltose and isomaltose-like substrates (palatinose, α-methylglucoside) were not, confirming that BaAG2 is a maltase. BaAG2 was competitively inhibited by a diabetes drug acarbose (Ki = 0.8 µM) and Tris (Ki = 70.5 µM). BaAG2 was competitively inhibited also by isomaltose-like sugars and a hydrolysis product—glucose. At high maltose concentrations, BaAG2 exhibited transglycosylating ability producing potentially prebiotic di- and trisaccharides. Atypically for yeast maltases, a low but clearly recordable exo-hydrolytic activity on amylose, amylopectin and glycogen was detected. Saccharomyces cerevisiae maltase MAL62, studied for comparison, had only minimal ability to hydrolyze these polymers, and its transglycosylating activity was about three times lower compared to BaAG2. Sequence identity of BaAG2 with other maltases was only moderate being the highest (51%) with the maltase MalT of Aspergillus oryzae.

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Higgins, Vincent J., Mark Braidwood, Phil Bell, Peter Bissinger, Ian W. Dawes e Paul V. Attfield. "Genetic Evidence That High Noninduced Maltase and Maltose Permease Activities, Governed by MALx3-Encoded Transcriptional Regulators, Determine Efficiency of Gas Production by Baker’s Yeast in Unsugared Dough". Applied and Environmental Microbiology 65, n.º 2 (1 de fevereiro de 1999): 680–85. http://dx.doi.org/10.1128/aem.65.2.680-685.1999.

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ABSTRACT Strain selection and improvement in the baker’s yeast industry have aimed to increase the speed of maltose fermentation in order to increase the leavening activity of industrial baking yeast. We identified two groups of baker’s strains of Saccharomyces cerevisiae that can be distinguished by the mode of regulation of maltose utilization. One group (nonlagging strains), characterized by rapid maltose fermentation, had at least 12-fold more maltase and 130-fold-higher maltose permease activities than maltose-lagging strains in the absence of inducing sugar (maltose) and repressing sugar (glucose). Increasing the noninduced maltase activity of a lagging strain 13-fold led to an increase in CO2 production in unsugared dough. This increase in CO2 production also was seen when the maltose permease activity was increased 55-fold. Only when maltase and maltose permease activities were increased in concert was CO2 production by a lagging strain similar to that of a nonlagging strain. The noninduced activities of maltase and maltose permease constitute the largest determinant of whether a strain displays a nonlagging or a lagging phenotype and are dependent upon theMALx3 allele. Previous strategies for strain improvement have targeted glucose derepression of maltase and maltose permease expression. Our results suggest that increasing noninduced maltase and maltose permease levels is an important target for improved maltose metabolism in unsugared dough.

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Houghton-Larsen, Jens, e Anders Brandt. "Fermentation of High Concentrations of Maltose by Saccharomyces cerevisiae Is Limited by the COMPASS Methylation Complex". Applied and Environmental Microbiology 72, n.º 11 (15 de setembro de 2006): 7176–82. http://dx.doi.org/10.1128/aem.01704-06.

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ABSTRACT In Saccharomyces cerevisiae, genes encoding maltose permeases and maltases are located in the telomeric regions of different chromosomes. The COMPASS methylation complex, which methylates lysine 4 on histone H3, controls the silencing of telomeric regions. Yeast strains deleted for SWD1, SWD3, SDC1, SET1, BRE2, or SPP1, encoding components of the COMPASS complex, fermented a medium containing 22% maltose with noticeably higher attenuation than did the wild type, resulting in production of up to 29% more ethanol. The least effective strain was spp1. Absence of COMPASS components had no effect on the fermentation of media with 20% glucose, 20% sucrose, or 16% maltose. Deletion of SWD3 resulted in larger amounts of MAL12 transcript, encoding maltase, at the late stages of fermentation of 22% maltose. A similar effect on maltase activity and maltose uptake capability was seen. The lysine 4 residue of histone H3 was trimethylated in wild-type cells at the late stages, while only small amounts of the dimethylated form were detected. Trimethylation and dimethylation of this residue were not detected in strains deleted for SWD1, SWD3, SET1, BRE2, or SDC1. Trimethylated lysine 4 was apparent only at the early stages (48 and 96 h) of fermentation in an spp1 strain. This work indicates that the COMPASS complex represses the expression of maltose utilization genes during the late stages of fermentation of a high concentration of maltose.

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WIMMER, Bernhard, Friedrich LOTTSPEICH, Johannes RITTER e Karin BRONNENMEIER. "A novel type of thermostable α-D-glucosidase from Thermoanaerobacter thermohydrosulfuricus exhibiting maltodextrinohydrolase activity". Biochemical Journal 328, n.º 2 (1 de dezembro de 1997): 581–86. http://dx.doi.org/10.1042/bj3280581.

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An α-glucosidase with the ability to attack polymeric substrates was purified to homogeneity from culture supernatants of Thermoanaerobacter thermohydrosulfuricus DSM 567. The enzyme is apparently a glycoprotein with a molecular mass of 160 kDa. Maximal activity is observed between pH 5 and 7 at 75 °C. The α-glucosidase is active towards p-nitrophenyl-α-D-glucoside, maltose, malto-oligosaccharides, starch and pullulan. Highest activity is displayed towards the disaccharide maltose. In addition to glucose, maltohexaose and maltoheptaose can be detected as the initial products of starch hydrolysis. After short incubations of pullulan, glucose is found as the only product. At high substrate concentrations, maltose and malto-oligosaccharide, but not glucose, are used as acceptors for glucosyl-transfer. These findings indicate that the T. thermohydrosulfuricus enzyme represents a novel type of α-glucosidase exhibiting maltase, glucohydrolase and ‘maltodextrinohydrolase’ activity.

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Ferreira, Julio C., Anita D. Panek e Pedro S. de Araujo. "Inactivation of maltose permease and maltase in sporulatingSaccharomyces cerevisiae". Canadian Journal of Microbiology 46, n.º 4 (1 de abril de 2000): 383–86. http://dx.doi.org/10.1139/w99-136.

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Maltose transport and maltase activities were inactivated during sporulation of a MAL constitutive yeast strain harboring different MAL loci. Both activities were reduced to almost zero after 5 h of incubation in sporulation medium. The inactivation of maltase and maltose permease seems to be related to optimal sporulation conditions such as a suitable supply of oxygen and cell concentration in the sporulating cultures, and occurs in the fully derepressed conditions of incubation in the sporulation acetate medium. The inactivation of maltase and maltose permease under sporulation conditions in MAL constitutive strains suggests an alternative mechanism for the regulation of the MAL gene expression during the sporulation process.Key words: maltase activity, maltose permease activity, sporulation, Saccharomyces cerevisiae.

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Dubin, R. A., E. L. Perkins, R. B. Needleman e C. A. Michels. "Identification of a second trans-acting gene controlling maltose fermentation in Saccharomyces carlsbergensis". Molecular and Cellular Biology 6, n.º 8 (agosto de 1986): 2757–65. http://dx.doi.org/10.1128/mcb.6.8.2757-2765.1986.

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Maltose fermentation in Saccharomyces spp. requires the presence of a dominant MAL locus. The MAL6 locus has been cloned and shown to encode the structural genes for maltose permease (MAL61), maltase (MAL62), and a positively acting regulatory gene (MAL63). Induction of the MAL61 and MAL62 gene products requires the presence of maltose and the MAL63 gene. Mutations within the MAL63 gene produce nonfermenting strains unable to induce the two structural gene products. Reversion of these mal63 nonfermenters to maltose fermenters nearly always leads to the constitutive expression of maltase and maltose permease, and constitutivity is always linked to MAL6. We demonstrated that for one such revertant, strain C2, constitutivity did not require the MAL63 gene, since deletion disruption of this gene did not affect the constitutive expression of the structural genes. In addition, constitutivity was trans acting. Deletion disruption of the MAL6-linked structural genes for maltase and maltose permease in this strain did not affect the constitutive expression of a second, unlinked maltase structural gene. We isolated new maltose-fermenting revertants of a nonfermenting strain which carried a deletion disruption of the MAL63 gene. All 16 revertants isolated expressed maltase constitutively. In one revertant studied in detail, strain R10, constitutive expression was demonstrated to be linked to MAL6, semidominant, trans acting, and residing outside the MAL63-MAL61-MAL62 genes. From these studies we propose the existence of a second trans-acting regulatory gene at the MAL6 locus. We call this new gene MAL64. We mapped the MAL64 gene 2.3 centimorgans to the left of MAL63. The role of the MAL64 gene product in maltose fermentation is discussed.

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Dubin, R. A., E. L. Perkins, R. B. Needleman e C. A. Michels. "Identification of a second trans-acting gene controlling maltose fermentation in Saccharomyces carlsbergensis." Molecular and Cellular Biology 6, n.º 8 (agosto de 1986): 2757–65. http://dx.doi.org/10.1128/mcb.6.8.2757.

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Maltose fermentation in Saccharomyces spp. requires the presence of a dominant MAL locus. The MAL6 locus has been cloned and shown to encode the structural genes for maltose permease (MAL61), maltase (MAL62), and a positively acting regulatory gene (MAL63). Induction of the MAL61 and MAL62 gene products requires the presence of maltose and the MAL63 gene. Mutations within the MAL63 gene produce nonfermenting strains unable to induce the two structural gene products. Reversion of these mal63 nonfermenters to maltose fermenters nearly always leads to the constitutive expression of maltase and maltose permease, and constitutivity is always linked to MAL6. We demonstrated that for one such revertant, strain C2, constitutivity did not require the MAL63 gene, since deletion disruption of this gene did not affect the constitutive expression of the structural genes. In addition, constitutivity was trans acting. Deletion disruption of the MAL6-linked structural genes for maltase and maltose permease in this strain did not affect the constitutive expression of a second, unlinked maltase structural gene. We isolated new maltose-fermenting revertants of a nonfermenting strain which carried a deletion disruption of the MAL63 gene. All 16 revertants isolated expressed maltase constitutively. In one revertant studied in detail, strain R10, constitutive expression was demonstrated to be linked to MAL6, semidominant, trans acting, and residing outside the MAL63-MAL61-MAL62 genes. From these studies we propose the existence of a second trans-acting regulatory gene at the MAL6 locus. We call this new gene MAL64. We mapped the MAL64 gene 2.3 centimorgans to the left of MAL63. The role of the MAL64 gene product in maltose fermentation is discussed.

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Charron, M. J., e C. A. Michels. "The naturally occurring alleles of MAL1 in Saccharomyces species evolved by various mutagenic processes including chromosomal rearrangement." Genetics 120, n.º 1 (1 de setembro de 1988): 83–93. http://dx.doi.org/10.1093/genetics/120.1.83.

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Abstract In order for a yeast strain to ferment maltose it must contain any one of the five dominant MAL loci. Each dominant MAL locus thus far analyzed contains three genes: GENE 1, encoding maltose permease, GENE 2 encoding maltase and GENE 3 encoding a positive trans-acting regulatory protein. In addition to these dominant MAL loci, several naturally occurring, partially functional alleles of MAL1 and MAL3 have been identified. Here, we present genetic and molecular analysis of the three partially functional alleles of MAL1: the MAL1p allele which can express only the MAL activator; the MAL1 g allele which can express both a maltose permease and maltase; and the mal1(0) allele which can express only maltase. Based on our results, we propose that the MAL1p, MAL1g and mal1(0) alleles evolved from the dominant MAL1 locus by a series of rearrangements and/or deletions of this yeast telomere-associated locus as well as by other mutagenic processes of gene inactivation. One surprising finding is that the MAL1g-encoded maltose permease exhibits little sequence homology to the MAL1-encoded maltose permease though they appear to be functionally homologous.

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Hong, S. H., e J. Marmur. "Upstream regulatory regions controlling the expression of the yeast maltase gene". Molecular and Cellular Biology 7, n.º 7 (julho de 1987): 2477–83. http://dx.doi.org/10.1128/mcb.7.7.2477-2483.1987.

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The expression of the maltase (MALS) and the maltose permease (MALT) genes in Saccharomyces species is coregulated at the transcriptional level; they are coordinately induced by maltose in the presence of a positively acting regulatory (MALR) gene and carbon catabolite repressed by glucose. We generated a series of deletions in the upstream region of the MAL6S gene to examine the regulatory elements in detail. The results showed that inducible expression by maltose was lost when the region between 320 and 380 base pairs upstream of the translation initiation codon was deleted. This region contained an imperfect inverted repeat sequence (-361 to -327) or four copies of short direct repeats that might serve as components of the upstream activation site (UASM) for the maltase gene, or both. When a stretch of T-rich sequence (-253 to -237) was deleted, the susceptibility of the maltase gene to carbon catabolite repression was affected.

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Hong, S. H., e J. Marmur. "Upstream regulatory regions controlling the expression of the yeast maltase gene." Molecular and Cellular Biology 7, n.º 7 (julho de 1987): 2477–83. http://dx.doi.org/10.1128/mcb.7.7.2477.

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The expression of the maltase (MALS) and the maltose permease (MALT) genes in Saccharomyces species is coregulated at the transcriptional level; they are coordinately induced by maltose in the presence of a positively acting regulatory (MALR) gene and carbon catabolite repressed by glucose. We generated a series of deletions in the upstream region of the MAL6S gene to examine the regulatory elements in detail. The results showed that inducible expression by maltose was lost when the region between 320 and 380 base pairs upstream of the translation initiation codon was deleted. This region contained an imperfect inverted repeat sequence (-361 to -327) or four copies of short direct repeats that might serve as components of the upstream activation site (UASM) for the maltase gene, or both. When a stretch of T-rich sequence (-253 to -237) was deleted, the susceptibility of the maltase gene to carbon catabolite repression was affected.

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Vongsangnak, Wanwipa, Margarita Salazar, Kim Hansen e Jens Nielsen. "Genome-wide analysis of maltose utilization and regulation in aspergilli". Microbiology 155, n.º 12 (1 de dezembro de 2009): 3893–902. http://dx.doi.org/10.1099/mic.0.031104-0.

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Maltose utilization and regulation in aspergilli is of great importance for cellular physiology and industrial fermentation processes. In Aspergillus oryzae, maltose utilization requires a functional MAL locus, composed of three genes: MALR encoding a regulatory protein, MALT encoding maltose permease and MALS encoding maltase. Through a comparative genome and transcriptome analysis we show that the MAL regulon system is active in A. oryzae while it is not present in Aspergillus niger. In order to utilize maltose, A. niger requires a different regulatory system that involves the AmyR regulator for glucoamylase (glaA) induction. Analysis of reporter metabolites and subnetworks illustrates the major route of maltose transport and metabolism in A. oryzae. This demonstrates that overall metabolic responses of A. oryzae occur in terms of genes, enzymes and metabolites when the carbon source is altered. Although the knowledge of maltose transport and metabolism is far from being complete in Aspergillus spp., our study not only helps to understand the sugar preference in industrial fermentation processes, but also indicates how maltose affects gene expression and overall metabolism.

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Jones, C. R., M. Ray, K. A. Dawson e H. J. Strobel. "High-Affinity Maltose Binding and Transport by the Thermophilic Anaerobe Thermoanaerobacter ethanolicus 39E". Applied and Environmental Microbiology 66, n.º 3 (1 de março de 2000): 995–1000. http://dx.doi.org/10.1128/aem.66.3.995-1000.2000.

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ABSTRACT Thermoanaerobacter ethanolicus is a gram-positive thermophile that produces considerable amounts of ethanol from soluble sugars and polymeric substrates, including starch. Growth on maltose, a product of starch hydrolysis, was associated with the production of a prominent membrane-associated protein that had an apparent molecular weight of 43,800 and was not detected in cells grown on xylose or glucose. Filter-binding assays revealed that cell membranes bound maltose with high affinity. Metabolic labeling ofT. ethanolicus maltose-grown cells with [14C]palmitic acid showed that this protein was posttranslationally acylated. A maltose-binding protein was purified by using an amylose resin affinity column, and the binding constant was 270 nM. Since maltase activity was found only in the cytosol of fractionated cells and unlabeled glucose did not compete with radiolabeled maltose for uptake in whole cells, it appeared that maltose was transported intact. In whole-cell transport assays, the affinity for maltose was approximately 40 nM. Maltotriose and α-trehalose competitively inhibited maltose uptake in transport assays, whereas glucose, cellobiose, and a range of disaccharides had little effect. Based on these results, it appears that T. ethanolicus possesses a high-affinity, ABC type transport system that is specific for maltose, maltotriose, and α-trehalose.

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Cvetkovic, Jelena, Ilka Haferkamp, Regina Rode, Isabel Keller, Benjamin Pommerrenig, Oliver Trentmann, Jacqueline Altensell et al. "Ectopic maltase alleviates dwarf phenotype and improves plant frost tolerance of maltose transporter mutants". Plant Physiology 186, n.º 1 (26 de fevereiro de 2021): 315–29. http://dx.doi.org/10.1093/plphys/kiab082.

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Abstract Maltose, the major product of starch breakdown in Arabidopsis (Arabidopsis thaliana) leaves, exits the chloroplast via the maltose exporter1 MEX1. Consequently, mex1 loss-of-function plants exhibit substantial maltose accumulation, a starch-excess phenotype and a specific chlorotic phenotype during leaf development. Here, we investigated whether the introduction of an alternative metabolic route could suppress the marked developmental defects typical for mex1 loss-of-function mutants. To this end, we ectopically expressed in mex1chloroplasts a functional maltase (MAL) from baker’s yeast (Saccharomyces cerevisiae, chloroplastidial MAL [cpMAL] mutants). Remarkably, the stromal MAL activity substantially alleviates most phenotypic peculiarities typical for mex1 plants. However, the cpMAL lines contained only slightly less maltose than parental mex1 plants and their starch levels were, surprisingly, even higher. These findings point to a threshold level of maltose responsible for the marked developmental defects in mex1. While growth and flowering time were only slightly retarded, cpMAL lines exhibited a substantially improved frost tolerance, when compared to wild-types. In summary, these results demonstrate the possibility to bypass the MEX1 transporter, allow us to differentiate between possible starch-excess and maltose-excess responses, and demonstrate that stromal maltose accumulation prevents frost defects. The latter insight may be instrumental for the development of crop plants with improved frost tolerance.

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Pereira, B., e S. Sivakami. "A comparison of the active site of maltase-glucoamylase from the brush border of rabbit small intestine and kidney by chemical modification studies". Biochemical Journal 274, n.º 2 (1 de março de 1991): 349–54. http://dx.doi.org/10.1042/bj2740349.

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The neutral maltase-glucoamylase complex has been purified to homogeneity from the brush-border membrane of rabbit intestine and kidney. Chemical modification of the amino acid side chains was carried out on the purified enzymes. Studies on the kidney enzyme revealed that tryptophan, histidine and cysteine were essential for both maltase and glucoamylase activities, whereas tryptophan, histidine and lysine were essential for the maltase and glucoamylase activities of the intestinal enzyme. Though there was no difference in the amino acids essential for the hydrolysis of maltose and starch by any one enzyme, starch hydrolysis seems to require two histidine residues instead of the one which is required for maltose hydrolysis. This appears to be true for both the intestinal and kidney enzymes.

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Ni, B. F., e R. B. Needleman. "Identification of the upstream activating sequence of MAL and the binding sites for the MAL63 activator of Saccharomyces cerevisiae". Molecular and Cellular Biology 10, n.º 7 (julho de 1990): 3797–800. http://dx.doi.org/10.1128/mcb.10.7.3797-3800.1990.

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Maltose fermentation in Saccharomyces species requires the presence of at least one of five unlinked MAL loci: MAL1, MAL2, MAL3, MAL4, and MAL6. Each of these loci consists of a complex of genes involved in maltose metabolism; the complex includes maltase, a maltose permease, and an activator of these genes. At the MAL6 locus, the activator is encoded by the MAL63 gene. While the MAL6 locus has been the subject of numerous studies, the binding sites of the MAL63 activator have not been determined. In this study, we used Escherichia coli extracts containing the MAL63 protein to define the binding sites of the MAL63 protein in the divergently transcribed MAL61-62 promotor. When a DNA fragment containing these sites was placed upstream of a CYC1-lacZ gene, maltose induced beta-galactosidase. These sites therefore constitute an upstream activating sequence for the MAL genes.

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Ni, B. F., e R. B. Needleman. "Identification of the upstream activating sequence of MAL and the binding sites for the MAL63 activator of Saccharomyces cerevisiae." Molecular and Cellular Biology 10, n.º 7 (julho de 1990): 3797–800. http://dx.doi.org/10.1128/mcb.10.7.3797.

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Maltose fermentation in Saccharomyces species requires the presence of at least one of five unlinked MAL loci: MAL1, MAL2, MAL3, MAL4, and MAL6. Each of these loci consists of a complex of genes involved in maltose metabolism; the complex includes maltase, a maltose permease, and an activator of these genes. At the MAL6 locus, the activator is encoded by the MAL63 gene. While the MAL6 locus has been the subject of numerous studies, the binding sites of the MAL63 activator have not been determined. In this study, we used Escherichia coli extracts containing the MAL63 protein to define the binding sites of the MAL63 protein in the divergently transcribed MAL61-62 promotor. When a DNA fragment containing these sites was placed upstream of a CYC1-lacZ gene, maltose induced beta-galactosidase. These sites therefore constitute an upstream activating sequence for the MAL genes.

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Koning, Sonja M., Wil N. Konings e Arnold J. M. Driessen. "Biochemical evidence for the presence of two α-glucoside ABC-transport systems in the hyperthermophilic archaeonPyrococcus furiosus". Archaea 1, n.º 1 (2002): 19–25. http://dx.doi.org/10.1155/2002/529610.

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The hyperthermophilic archaeonPyrococcus furiosuscan utilize different carbohydrates, such as starch, maltose and trehalose. Uptake of α-glucosides is mediated by two different, binding protein-dependent, ATP-binding cassette (ABC)-type transport systems. The maltose transporter also transports trehalose, whereas the maltodextrin transport system mediates the uptake of maltotriose and higher malto-oligosaccharides, but not maltose. Both transport systems are induced during growth on their respective substrates.

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Fogarty, William M., Catherine T. Kelly e Sunil K. Kadam. "Separation and characterization of an α-glucosidase and maltase from Bacillus amyloliquefaciens". Canadian Journal of Microbiology 31, n.º 8 (1 de agosto de 1985): 670–74. http://dx.doi.org/10.1139/m85-127.

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A novel α-glucosidase and a maltase were isolated from Bacillus amyloliquefaciens. The formation of both enzymes was induced by trehalose, sucrose, or lactose in the growth medium. Trehalose is by far the most efficient inducer of both systems. The α-glucosidase and maltase were separated and purified by ion-exchange chromatography on DEAE Bio-Gel A. Purified α-glucosidase hydrolysed p-nitrophenyl-α-D-glucoside, isomaltose, and isomaltotriose but sucrose, maltose, or related saccharides were not attacked. β-Glucosides and polymeric glucosides were not degraded. The optimum temperature for α-glucosidase activity was 40 °C and its pH optimum was 5.3. The molecular weight and isoelectric point (pI) of the enzyme were 27 000 and 4.6, respectively. Purified maltase attacked maltose and sucrose, while maltotriose and melezitose were hydrolysed at slower rates and p-nitrophenyl-α-D-glucoside was not degraded. Other properties of the maltase were as follows: optimum temperature for activity, 30 °C; pH optimum, 6.5; molecular weight, 64 000; and pI, 4.7.

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Dubin, R. A., M. J. Charron, S. R. Haut, R. B. Needleman e C. A. Michels. "Constitutive expression of the maltose fermentative enzymes in Saccharomyces carlsbergensis is dependent upon the mutational activation of a nonessential homolog of MAL63". Molecular and Cellular Biology 8, n.º 3 (março de 1988): 1027–35. http://dx.doi.org/10.1128/mcb.8.3.1027-1035.1988.

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Maltose fermentation in Saccharomyces carlsbergensis is dependent upon the MAL6 locus. This complex locus is composed of the MAL61 and MAL62 genes, which encode maltose permease and maltase, respectively, and a third gene, MAL63, which codes for a trans-acting positive regulatory product. In wild-type strains, expression of the MAL61 and MAL62 mRNAs and proteins is induced by maltose and induction is dependent upon the MAL63 gene. Mutants constitutively expressing the MAL61 and MAL62 gene products have been isolated in mal63 backgrounds, and the mutations which have been analyzed map to a fourth MAL6-linked gene, MAL64. Cloning and characterization of this new gene are described in this report. The results revealed that the MAL64-C alleles present in constitutive strains encode a trans-acting positive function required for constitutive expression of the MAL61 and MAL62 gene products. In inducible strains, the MAL64 gene is dispensable, as deletion of the gene had no effect on maltose fermentation or maltose-regulated induction. MAL64 encoded transcripts of 2.0 and 1.4 kilobase pairs. While both MAL64 mRNAs were constitutively expressed in constitutive strains, they were maltose inducible in wild-type strains and induction was dependent upon the MAL63 gene. The MAL63 and MAL64 genes are at least partially structurally homologous, suggesting that they control MAL61 and MAL62 transcript accumulation by similar mechanisms.

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Dubin, R. A., M. J. Charron, S. R. Haut, R. B. Needleman e C. A. Michels. "Constitutive expression of the maltose fermentative enzymes in Saccharomyces carlsbergensis is dependent upon the mutational activation of a nonessential homolog of MAL63." Molecular and Cellular Biology 8, n.º 3 (março de 1988): 1027–35. http://dx.doi.org/10.1128/mcb.8.3.1027.

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Maltose fermentation in Saccharomyces carlsbergensis is dependent upon the MAL6 locus. This complex locus is composed of the MAL61 and MAL62 genes, which encode maltose permease and maltase, respectively, and a third gene, MAL63, which codes for a trans-acting positive regulatory product. In wild-type strains, expression of the MAL61 and MAL62 mRNAs and proteins is induced by maltose and induction is dependent upon the MAL63 gene. Mutants constitutively expressing the MAL61 and MAL62 gene products have been isolated in mal63 backgrounds, and the mutations which have been analyzed map to a fourth MAL6-linked gene, MAL64. Cloning and characterization of this new gene are described in this report. The results revealed that the MAL64-C alleles present in constitutive strains encode a trans-acting positive function required for constitutive expression of the MAL61 and MAL62 gene products. In inducible strains, the MAL64 gene is dispensable, as deletion of the gene had no effect on maltose fermentation or maltose-regulated induction. MAL64 encoded transcripts of 2.0 and 1.4 kilobase pairs. While both MAL64 mRNAs were constitutively expressed in constitutive strains, they were maltose inducible in wild-type strains and induction was dependent upon the MAL63 gene. The MAL63 and MAL64 genes are at least partially structurally homologous, suggesting that they control MAL61 and MAL62 transcript accumulation by similar mechanisms.

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Naumov, G. I., E. S. Naumova e C. A. Michels. "Genetic variation of the repeated MAL loci in natural populations of Saccharomyces cerevisiae and Saccharomyces paradoxus." Genetics 136, n.º 3 (1 de março de 1994): 803–12. http://dx.doi.org/10.1093/genetics/136.3.803.

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Abstract In Saccharomyces cerevisiae, the gene functions required to ferment the disaccharide maltose are encoded by the MAL loci. Any one of five highly sequence homologous MAL loci identified in various S. cerevisiae strains (called MAL1, 2, 3, 4 and 6) is sufficient to ferment maltose. Each is a complex of three genes encoding maltose permease, maltase and a transcription activator. This family of loci maps to telomere-linked positions on different chromosomes and most natural strains contain more than one MAL locus. A number of naturally occurring, mutant alleles of MAL1 and MAL3 have been characterized which lack one or more of the gene functions encoded by the fully functional MAL loci. Loss of these gene functions appears to have resulted from mutation and/or rearrangement within the locus. Studies to date concentrated on the standard maltose fermenting strains of S. cerevisiae available from the Berkeley Yeast Stock Center collection. In this report we extend our genetic analysis of the MAL loci to a number of maltose fermenting and nonfermenting natural strains of S. cerevisiae and Saccharomyces paradoxus. No new MAL loci were discovered but several new mutant alleles of MAL1 were identified. The evolution of this gene family is discussed.

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Schönert, Stefan, Thomas Buder e Michael K. Dahl. "Identification and Enzymatic Characterization of the Maltose-Inducible α-Glucosidase MalL (Sucrase-Isomaltase-Maltase) of Bacillus subtilis". Journal of Bacteriology 180, n.º 9 (1 de maio de 1998): 2574–78. http://dx.doi.org/10.1128/jb.180.9.2574-2578.1998.

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ABSTRACT A gene coding for a putative α-glucosidase has been identified in the open reading frame yvdL (now termed malL), which was sequenced as part of the Bacillus subtilis genome project. The enzyme was overproduced in Escherichia coliand purified. Further analyses indicate that MalL is a specific oligo-1,4-1,6-α-glucosidase (sucrase-maltase-isomaltase). MalL expression in B. subtilis requires maltose induction and is subject to carbon catabolite repression by glucose and fructose. Insertional mutagenesis of malL resulted in a complete inactivation of the maltose-inducible α-glucosidase activity in crude protein extracts and a Mal− phenotype.

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Kelly, Catherine T., Mary Giblin e William M. Fogarty. "Resolution, purification, and characterization of two extracellular glucohydrolases, α-glucosidase and maltase, of Bacillus licheniformis". Canadian Journal of Microbiology 32, n.º 4 (1 de abril de 1986): 342–47. http://dx.doi.org/10.1139/m86-066.

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Two extracellular α-glucosidases (EC 3.2.1.20, α-D-glucoside glucohydrolase) of Bacillus licheniformis NCIB 8549 were separated, purified, and partially characterized. Resolution of the complex into two separate enzymes was achieved using Sephadex G-150. The first of these activities, a maltase, hydrolysed maltose preferentially. It had slight activity on isomaltose, p-nitrophenyl-α-D-glycopyranoside, and sucrose. The pH optimum was 6.0 and the molecular weight determined on Sephadex G-200 was 160 000. This enzyme did not display any transglucosylation activity. The second enzyme was an α-glucosidase. It displayed highest activity on p-nitrophenyl-α-D-glucopyranoside, followed by isomaltose, sucrose, and maltose. As with the maltase, the pH optimum was 6.0 and the molecular weight as determined on Sephadex G-150 was 66 000. With isomaltose and maltotriose as substrates, transglucosylation activity was evident.

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Kays, Stanley J., Jyh-Bin Sun e Ray F. Severson. "CRITICAL VOLATILES IN THE FIAVOR OF THE SWEETPOTATO". HortScience 28, n.º 4 (abril de 1993): 277E—277. http://dx.doi.org/10.21273/hortsci.28.4.277e.

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Changes in the concentration of individual sugars in sweetpotato storage roots with cooking and their relationship to the formation of volatile compounds were studied. During cooking maltose concentration increased from 0.03% fwt at 25.C to a maximum of 4.33% at WC. Microwave pretreatment (2-4 minutes) resulted in a significant decrease in amounts of maltose and volatiles formed. At 80°C, approximately 80% of maltose synthesis was inhibited when pretreated with microwaves. Adding maltose into microwave pretreated samples and then cooking in a convection oven restored most of the volatile profile with the exception of phenylacetaldehyde. Upon heating (200°C), sweetpotato root material that was insoluble in both methanol and methylene chloride produced similar volatile profiles to those from sweetpotatoes baked conventionally. Volatiles derived via thermal degradation of the non-polar methylenc chloride fraction and the polar methanol fraction did not display chromatographic profiles similar to those from conventionally baked sweetpotatoes. Initial reactions in the formation of critical volatiles appear to occur in the methanol and methylene chloride insoluble components. Maltol (3-hydroxy-2-methyl-4-pyrone) was found to be one of the critical components making up the characteristic aroma of baked sweetpotatoes. It was concluded that maltose represents a primary precursor for many of the volatile compounds emanating from baked `Jewel' sweetpotatoes and the formation of these volatiles appears to involve both enzymatic and thermal reactions.

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Wang, Xin, Mehtap Bali, Igor Medintz e Corinne A. Michels. "Intracellular Maltose Is Sufficient To Induce MAL Gene Expression in Saccharomyces cerevisiae". Eukaryotic Cell 1, n.º 5 (outubro de 2002): 696–703. http://dx.doi.org/10.1128/ec.1.5.696-703.2002.

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ABSTRACT The presence of maltose induces MAL gene expression in Saccharomyces cells, but little is known about how maltose is sensed. Strains with all maltose permease genes deleted are unable to induce MAL gene expression. In this study, we examined the role of maltose permease in maltose sensing by substituting a heterologous transporter for the native maltose permease. PmSUC2 encodes a sucrose transporter from the dicot plant Plantago major that exhibits no significant sequence homology to maltose permease. When expressed in Saccharomyces cerevisiae, PmSUC2 is capable of transporting maltose, albeit at a reduced rate. We showed that introduction of PmSUC2 restores maltose-inducible MAL gene expression to a maltose permease-null mutant and that this induction requires the MAL activator. These data indicate that intracellular maltose is sufficient to induce MAL gene expression independently of the mechanism of maltose transport. By using strains expressing defective mal61 mutant alleles, we demonstrated a correlation between the rate of maltose transport and the level of the induction, which is particularly evident in medium containing very limiting concentrations of maltose. Moreover, our results indicate that a rather low concentration of intracellular maltose is needed to trigger MAL gene expression. We also showed that constitutive overexpression of either MAL61 maltose permease or PmSUC2 suppresses the noninducible phenotype of a defective mal13 MAL-activator allele, suggesting that this suppression is solely a function of maltose transport activity and is not specific to the sequence of the permease. Our studies indicate that maltose permease does not function as the maltose sensor in S. cerevisiae.

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Lee, Eun Young, Shuji Kaneko, Promsuk Jutabha, Xilin Zhang, Susumu Seino, Takahito Jomori, Naohiko Anzai e Takashi Miki. "Distinct action of the α-glucosidase inhibitor miglitol on SGLT3, enteroendocrine cells, and GLP1 secretion". Journal of Endocrinology 224, n.º 3 (8 de dezembro de 2014): 205–14. http://dx.doi.org/10.1530/joe-14-0555.

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Oral ingestion of carbohydrate triggers glucagon-like peptide 1 (GLP1) secretion, but the molecular mechanism remains elusive. By measuring GLP1 concentrations in murine portal vein, we found that the ATP-sensitive K+(KATP) channel is not essential for glucose-induced GLP1 secretion from enteroendocrine L cells, while the sodium-glucose co-transporter 1 (SGLT1) is required, at least in the early phase (5 min) of secretion. By contrast, co-administration of the α-glucosidase inhibitor (α-GI) miglitol plus maltose evoked late-phase secretion in a glucose transporter 2-dependent manner. We found that GLP1 secretion induced by miglitol plus maltose was significantly higher than that by another α-GI, acarbose, plus maltose, despite the fact that acarbose inhibits maltase more potently than miglitol. As miglitol activates SGLT3, we compared the effects of miglitol on GLP1 secretion with those of acarbose, which failed to depolarize theXenopus laevisoocytes expressing human SGLT3. Oral administration of miglitol activated duodenal enterochromaffin (EC) cells as assessed by immunostaining of phosphorylated calcium–calmodulin kinase 2 (phospho-CaMK2). In contrast, acarbose activated much fewer enteroendocrine cells, having only modest phospho-CaMK2 immunoreactivity. Single administration of miglitol triggered no GLP1 secretion, and GLP1 secretion by miglitol plus maltose was significantly attenuated by atropine pretreatment, suggesting regulation via vagal nerve. Thus, while α-GIs generally delay carbohydrate absorption and potentiate GLP1 secretion, miglitol also activates duodenal EC cells, possibly via SGLT3, and potentiates GLP1 secretion through the parasympathetic nervous system.

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Strocchi, A., G. Corazza, J. Furne, C. Fine, A. Di Sario, G. Gasbarrini e M. D. Levitt. "Measurements of the jejunal unstirred layer in normal subjects and patients with celiac disease". American Journal of Physiology-Gastrointestinal and Liver Physiology 270, n.º 3 (1 de março de 1996): G487—G491. http://dx.doi.org/10.1152/ajpgi.1996.270.3.g487.

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Normal intestinal absorption of nutrients requires efficient luminal mixing to deliver solute to the brush border. Lacking such mixing, the buildup of thick unstirred layers over the mucosa markedly retards absorption of rapidly transported compounds. Using a technique based on the kinetics of maltose hydrolysis, we measured the unstirred layer thickness of the jejunum of normal subjects and patients with celiac disease, as well as that of the normal rat. The jejunum of humans and rats was perfused with varying maltose concentrations, and the apparent Michaelis constant (Km) and maximal velocity (Vmax) of maltose hydrolysis were determined from double-reciprocal plots. The true Km of intestinal maltase was determined on mucosal biopsies. Unstirred layer thickness was calculated from the in vivo Vmax and apparent Km and the in vitro Km of maltase. The average unstirred layer thickness of 11 celiac patients (170 micron) was seven times greater than that of 3 controls (25 micron). The unstirred layer of each celiac exceeded that of the controls. A variety of factors could account for the less efficient luminal stirring observed in celiacs. Although speculative, villous contractility could be an important stirring mechanism that would be absent in celiacs with villous atrophy. This speculation was supported by the finding of a relatively thick unstirred layer (mean: 106 micron) in rats, an animal that lacks villous contractility. Because any increase in unstirred layer slows transport of rapidly absorbed compounds, poor stirring appears to represent a previously unrecognized defect that could contribute to malabsorption in celiac disease and, perhaps, in other intestinal disorders.

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Ikarashi, Nobutomo, Rumi Takeda, Kiyomi Ito, Wataru Ochiai e Kiyoshi Sugiyama. "The Inhibition of Lipase and Glucosidase Activities by Acacia Polyphenol". Evidence-Based Complementary and Alternative Medicine 2011 (2011): 1–8. http://dx.doi.org/10.1093/ecam/neq043.

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Acacia polyphenol (AP) extracted from the bark of the black wattle tree (Acacia mearnsii) is rich in unique catechin-like flavan-3-ols, such as robinetinidol and fisetinidol. In anin vitrostudy, we measured the inhibitory activity of AP on lipase and glucosidase. In addition, we evaluated the effects of AP on absorption of orally administered olive oil, glucose, maltose, sucrose and starch solution in mice. We found that AP concentration-dependently inhibited the activity of lipase, maltase and sucrase with an IC50of 0.95, 0.22 and 0.60 mg ml−1, respectively. In ICR mice, olive oil was administered orally immediately after oral administration of AP solution, and plasma triglyceride concentration was measured. We found that AP significantly inhibited the rise in plasma triglyceride concentration after olive oil loading. AP also significantly inhibited the rise in plasma glucose concentration after maltose and sucrose loading, and this effect was more potent against maltose. AP also inhibited the rise in plasma glucose concentration after glucose loading and slightly inhibited it after starch loading. Our results suggest that AP inhibits lipase and glucosidase activities, which leads to a reduction in the intestinal absorption of lipids and carbohydrates.

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Woloshuk, C. P., J. R. Cavaletto e T. E. Cleveland. "Inducers of Aflatoxin Biosynthesis from Colonized Maize Kernels Are Generated by an Amylase Activity from Aspergillus flavus". Phytopathology® 87, n.º 2 (fevereiro de 1997): 164–69. http://dx.doi.org/10.1094/phyto.1997.87.2.164.

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Aflatoxin biosynthesis was induced by compounds in filtrates (EF) obtained from cultures consisting of ground maize kernels colonized by Aspergillus flavus. The inducing activity increased to a maximum at 4 days of incubation and then decreased. Amylase activity was detected in the EF, suggesting that the inducers are products of starch degradation (glucose, maltose, and maltotriose). Analysis of the enzyme by isoelectric focusing electrophoresis indicated a single α-amylase with a pI of 4.3. No maltase or amyloglucosidase was detected in the EF. High-pressure liquid chromatography analysis of the EF indicated the presence of glucose, maltose, and maltotriose in near-equal molar concentrations (about 15 mM). With a β-glucuronidase (GUS) reporter assay consisting of A. flavus transformed with an aflatoxin gene promoter-GUS reporter gene fusion to monitor induction of aflatoxin biosynthesis, the minimum concentration of glucose, maltose, or maltotriose that induced measurable GUS activity was determined to be 1 mM. These results support the hypothesis that the best inducers of aflatoxin biosynthesis are carbon sources readily metabolized via glycolysis. They also suggest that α-amylase produced by A. flavus has a role in the induction of aflatoxin biosynthesis in infected maize kernels.

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Kuile, B. H. Ter, e M. Müller. "Maltose utilization by extracellular hydrolysis followed by glucose transport in Trichomonas vaginalis". Parasitology 110, n.º 1 (janeiro de 1995): 37–44. http://dx.doi.org/10.1017/s0031182000081026.

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The amitochondriate parasitic protist Trichomonas vaginalis can utilize either glucose or maltose as carbon and energy source. The mechanisms of maltose utilization were explored with uptake experiments using radio-isotope labelled maltose in combination with the silicone-oil centrifugation technique and enzymatic assays measuring maltose hydrolysis. The uptake of maltose label became saturated after 2–3 h. The uptake of maltose as a function of the external maltose concentration was linear at low concentrations with no further increase at higher levels, kinetics characteristic of reactions obeying Michaelis–Menten kinetics preceded by a diffusion-limited step. Increased viscosity of the medium resulted in decreased maltose uptake, indicating an extracellular location of the diffusion-limited step. Most of the cellular α-glucosidase activity of T. vaginalis was detected on the cell surface, suggesting that maltose is hydrolysed to glucose outside the cell. Glucose interfered more with maltose uptake, and maltose less with glucose uptake, than would be expected if 1 mol of maltose were the equivalent of 2 mol of glucose. This pattern of interaction indicated that the interference occurs before the common metabolic pathway and even before the transport step, supporting the idea of extracellular maltose hydrolysis. We conclude that maltose is hydrolysed to glucose in the boundary layer of the cell, a process akin to membrane digestion in vertebrate enterocytes and on the teguments of helminths. The glucose formed is then transported by the glucose carrier of the organism.

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Jansen, Mickel L. A., Pascale Daran-Lapujade, Johannes H. de Winde, Matthew D. W. Piper e Jack T. Pronk. "Prolonged Maltose-Limited Cultivation of Saccharomyces cerevisiae Selects for Cells with Improved Maltose Affinity and Hypersensitivity". Applied and Environmental Microbiology 70, n.º 4 (abril de 2004): 1956–63. http://dx.doi.org/10.1128/aem.70.4.1956-1963.2004.

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ABSTRACT Prolonged cultivation (>25 generations) of Saccharomyces cerevisiae in aerobic, maltose-limited chemostat cultures led to profound physiological changes. Maltose hypersensitivity was observed when cells from prolonged cultivations were suddenly exposed to excess maltose. This substrate hypersensitivity was evident from massive cell lysis and loss of viability. During prolonged cultivation at a fixed specific growth rate, the affinity for the growth-limiting nutrient (i.e., maltose) increased, as evident from a decreasing residual maltose concentration. Furthermore, the capacity of maltose-dependent proton uptake increased up to 2.5-fold during prolonged cultivation. Genome-wide transcriptome analysis showed that the increased maltose transport capacity was not primarily due to increased transcript levels of maltose-permease genes upon prolonged cultivation. We propose that selection for improved substrate affinity (ratio of maximum substrate consumption rate and substrate saturation constant) in maltose-limited cultures leads to selection for cells with an increased capacity for maltose uptake. At the same time, the accumulative nature of maltose-proton symport in S. cerevisiae leads to unrestricted uptake when maltose-adapted cells are exposed to a substrate excess. These changes were retained after isolation of individual cell lines from the chemostat cultures and nonselective cultivation, indicating that mutations were involved. The observed trade-off between substrate affinity and substrate tolerance may be relevant for metabolic engineering and strain selection for utilization of substrates that are taken up by proton symport.

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Yamasaki, Yoshiki, Susumu Nakashima e Haruyoshi Konno. "A novel alpha-glucosidase from the moss Scopelophila cataractae." Acta Biochimica Polonica 54, n.º 2 (15 de maio de 2007): 401–6. http://dx.doi.org/10.18388/abp.2007_3262.

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Scopelophila cataractae is a rare moss that grows on copper-containing soils. S. cataractae protonema was grown on basal MS medium containing copper. A starch-degrading activity was detected in homogenates of the protonema, after successive extraction with phosphate buffer and buffer containing 3 M LiCl. Buffer-soluble extract (BS) and LiCl-soluble extract (LS) readily hydrolyzed amylopectin to liberate only glucose, which shows that alpha-glucosidase (EC 3.2.1.20) in BS and LS hydrolyzed amylopectin. The K(m) value of BS for maltose was 0.427. The K(m) value of BS for malto-oligosaccharide decreased with an increase in the molecular mass of the substrate. The value for maltohexaose was 0.106, which is about four-fold lower than that for maltose. BS was divided into two fractions of alpha-glucosidase (BS-1 and BS-2) by isoelectric focusing. The isoelectric points of these two enzymes were determined to be 4.36 (BS-1) and 5.25 (BS-2) by analytical gel electrofocusing. The two enzymes readily hydrolyzed malto-oligosaccharides. The two enzymes also hydrolyzed amylose, amylopectin and soluble starch at a rate similar to that with maltose. The two enzymes readily hydrolyzed panose to liberate glucose and maltose (1 : 1), and the K(m) value of BS for panose was similar to that for maltotriose, whereas the enzymes hydrolyzed isomaltose only weakly. With regard to substrate specificity, the two enzymes in BS are novel alpha-glucosidases. The two enzymes also hydrolyzed beta-limit dextrin, which has many alpha-1,6-glucosidic linkages near the non-reducing ends, more strongly than maltose, which shows that they do not need a debranching enzyme for starch digestion. The starch-degrading activity of BS was not inhibited by p-chloromercuribenzoic acid or alpha-amylase inhibitor. When amylopectin was treated with BS and LS in phosphate buffer, pH 6.0, glucose, but not glucose-1-phosphate, was detected, showing that the extracts did not contain phosphorylase but did contain an alpha-glucosidase. These results show that alpha-glucosidases should be capable of complete starch digestion by themselves in cells of S. cataractae.

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Palevsky, Paul M. "Maltose-Induced Hyponatremia". Annals of Internal Medicine 118, n.º 7 (1 de abril de 1993): 526. http://dx.doi.org/10.7326/0003-4819-118-7-199304010-00007.

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Wagner, Michaela, Alexander Wagner, Xiaoqing Ma, Julia Christin Kort, Abhrajyoti Ghosh, Bernadette Rauch, Bettina Siebers e Sonja-Verena Albers. "Investigation of themalEPromoter and MalR, a Positive Regulator of the Maltose Regulon, for an Improved Expression System in Sulfolobus acidocaldarius". Applied and Environmental Microbiology 80, n.º 3 (22 de novembro de 2013): 1072–81. http://dx.doi.org/10.1128/aem.03050-13.

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ABSTRACTIn this study, the regulator MalR (Saci_1161) of the TrmB family fromSulfolobus acidocaldariuswas identified and was shown to be involved in transcriptional control of the maltose regulon (Saci_1660 to Saci_1666), including the ABC transporter (malEFGK), α-amylase (amyA), and α-glycosidase (malA). The ΔmalRdeletion mutant exhibited a significantly decreased growth rate on maltose and dextrin but not on sucrose. The expression of the genes organized in the maltose regulon was induced only in the presence of MalR and maltose in the growth medium, indicating that MalR, in contrast to its TrmB and TrmB-like homologues, is an activator of the maltose gene cluster. Electrophoretic mobility shift assays revealed that the binding of MalR tomalEwas independent of sugars. Here we report the identification of the archaeal maltose regulator protein MalR, which acts as an activator and controls the expression of genes involved in maltose transport and metabolic conversion inS. acidocaldarius, and its use for improvement of theS. acidocaldariusexpression system under the control of an optimized maltose binding protein (malE) promoter by promoter mutagenesis.

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Ferreira, Julio C., Anita D. Panek e Pedro S. de Araujo. "Inactivation of maltose permease and maltase in sporulating Saccharomyces cerevisiae". Canadian Journal of Microbiology 46, n.º 4 (2000): 383–86. http://dx.doi.org/10.1139/cjm-46-4-383.

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Dippel, Renate, e Winfried Boos. "The Maltodextrin System of Escherichia coli: Metabolism and Transport". Journal of Bacteriology 187, n.º 24 (15 de dezembro de 2005): 8322–31. http://dx.doi.org/10.1128/jb.187.24.8322-8331.2005.

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ABSTRACT The maltose/maltodextrin regulon of Escherichia coli consists of 10 genes which encode a binding protein-dependent ABC transporter and four enzymes acting on maltodextrins. All mal genes are controlled by MalT, a transcriptional activator that is exclusively activated by maltotriose. By the action of amylomaltase, we prepared uniformly labeled [14C]maltodextrins from maltose up to maltoheptaose with identical specific radioactivities with respect to their glucosyl residues, which made it possible to quantitatively follow the rate of transport for each maltodextrin. Isogenic malQ mutants lacking maltodextrin phosphorylase (MalP) or maltodextrin glucosidase (MalZ) or both were constructed. The resulting in vivo pattern of maltodextrin metabolism was determined by analyzing accumulated [14C]maltodextrins. MalP− MalZ+ strains degraded all dextrins to maltose, whereas MalP+ MalZ− strains degraded them to maltotriose. The labeled dextrins were used to measure the rate of transport in the absence of cytoplasmic metabolism. Irrespective of the length of the dextrin, the rates of transport at a submicromolar concentration were similar for the maltodextrins when the rate was calculated per glucosyl residue, suggesting a novel mode for substrate translocation. Strains lacking MalQ and maltose transacetylase were tested for their ability to accumulate maltose. At 1.8 nM external maltose, the ratio of internal to external maltose concentration under equilibrium conditions reached 106 to 1 but declined at higher external maltose concentrations. The maximal internal level of maltose at increasing external maltose concentrations was around 100 mM. A strain lacking malQ, malP, and malZ as well as glycogen synthesis and in which maltodextrins are not chemically altered could be induced by external maltose as well as by all other maltodextrins, demonstrating the role of transport per se for induction.

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Tarigan, Daniel. "SYNTHESIS OF SURFACTANS DILAUROYL MALTOSE THROUGH ACETILATION REACTION OF MALTOSE FOLLOWED BY TRANSESTERIFICATION REACTION WITH METHYL LAURATE". Indonesian Journal of Chemistry 9, n.º 3 (24 de junho de 2010): 445–51. http://dx.doi.org/10.22146/ijc.21513.

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Maltose has been partially acetylated from the reaction of melted maltose and acetic anhydride without solvent and catalyst to produce maltocyl acetate with the yield of 67%. Lauryc acid can be methanolized using H2SO4 as the catalyst to produce methyl laurate with the yield of 92%. The transesterification of methyl laurate and maltocyl acetate in methanol using sodium methoxyde as the catalyst at reflux, yielded a novel compound dilauroyl maltose after isolated by column chromatography, with the yield of 59%. Methyl laurate, maltocyl acetate, and dilauroyl maltose were confirmed by FT-IR and 'H-NMR spectroscopy, and the surface tension of dilauroyl maltose solution was determined by Du-Nuoy tensiometer to obtain the HLB value of 2.67. Keywords: Surfactant Transesterification, Maltose

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Hu, Zhen, Yingzi Yue, Hua Jiang, Bin Zhang, Peter W. Sherwood e Corinne A. Michels. "Analysis of the Mechanism by Which Glucose Inhibits Maltose Induction of MAL Gene Expression in Saccharomyces". Genetics 154, n.º 1 (1 de janeiro de 2000): 121–32. http://dx.doi.org/10.1093/genetics/154.1.121.

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Abstract Expression of the MAL genes required for maltose fermentation in Saccharomyces cerevisiae is induced by maltose and repressed by glucose. Maltose-inducible regulation requires maltose permease and the MAL-activator protein, a DNA-binding transcription factor encoded by MAL63 and its homologues at the other MAL loci. Previously, we showed that the Mig1 repressor mediates glucose repression of MAL gene expression. Glucose also blocks MAL-activator-mediated maltose induction through a Mig1p-independent mechanism that we refer to as glucose inhibition. Here we report the characterization of this process. Our results indicate that glucose inhibition is also Mig2p independent. Moreover, we show that neither overexpression of the MAL-activator nor elimination of inducer exclusion is sufficient to relieve glucose inhibition, suggesting that glucose acts to inhibit induction by affecting maltose sensing and/or signaling. The glucose inhibition pathway requires HXK2, REG1, and GSF1 and appears to overlap upstream with the glucose repression pathway. The likely target of glucose inhibition is Snf1 protein kinase. Evidence is presented indicating that, in addition to its role in the inactivation of Mig1p, Snf1p is required post-transcriptionally for the synthesis of maltose permease whose function is essential for maltose induction.

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Gould, Alister D., Patrick G. Telmer e Brian H. Shilton. "Stimulation of the Maltose Transporter ATPase by Unliganded Maltose Binding Protein". Biochemistry 48, n.º 33 (25 de agosto de 2009): 8051–61. http://dx.doi.org/10.1021/bi9007066.

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Ernits, Karin, Christian Kjeldsen, Karina Persson, Eliis Grigor, Tiina Alamäe e Triinu Visnapuu. "Structural Insight into a Yeast Maltase—The BaAG2 from Blastobotrys adeninivorans with Transglycosylating Activity". Journal of Fungi 7, n.º 10 (29 de setembro de 2021): 816. http://dx.doi.org/10.3390/jof7100816.

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An early-diverged yeast, Blastobotrys (Arxula) adeninivorans (Ba), has biotechnological potential due to nutritional versatility, temperature tolerance, and production of technologically applicable enzymes. We have biochemically characterized from the Ba type strain (CBS 8244) the GH13-family maltase BaAG2 with efficient transglycosylation activity on maltose. In the current study, transglycosylation of sucrose was studied in detail. The chemical entities of sucrose-derived oligosaccharides were determined using nuclear magnetic resonance. Several potentially prebiotic oligosaccharides with α-1,1, α-1,3, α-1,4, and α-1,6 linkages were disclosed among the products. Trisaccharides isomelezitose, erlose, and theanderose, and disaccharides maltulose and trehalulose were dominant transglycosylation products. To date no structure for yeast maltase has been determined. Structures of the BaAG2 with acarbose and glucose in the active center were solved at 2.12 and 2.13 Å resolution, respectively. BaAG2 exhibited a catalytic domain with a (β/α)8-barrel fold and Asp216, Glu274, and Asp348 as the catalytic triad. The fairly wide active site cleft contained water channels mediating substrate hydrolysis. Next to the substrate-binding pocket an enlarged space for potential binding of transglycosylation acceptors was identified. The involvement of a Glu (Glu309) at subsite +2 and an Arg (Arg233) at subsite +3 in substrate binding was shown for the first time for α-glucosidases.

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Liang, Xin Hong, Bin Li, Gang Li, Yu Tang e Zu Feng Guo. "Determination of Sugars in β-Amylase Hydrolysates by High Performance Liquid Chromatography". Advanced Materials Research 396-398 (novembro de 2011): 1575–78. http://dx.doi.org/10.4028/www.scientific.net/amr.396-398.1575.

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Abstract. The chromatographic conditions for the separation of glucose, maltose and maltotriose on a ZORBAX Eclipse XDB-C18 column (4 um, 4.6×250mm) by use of a 2414 differential refractometer detector were determined. The square of the correlation coefficient of glucose, sucrose, maltose and maltotriose was 0.9973, 0.9981, 0.9977 and 0.9987, respectively. When the ratio of signal and noise was 3, the detection limit of glucose, sucrose, maltose and maltotriose was 0.3, 0.3, 0.20, 0.20 mg/mL the β-amylase hydrolysates consisted mainly of maltose, and maltotriose next, glucose only in trace amount, and no sucrose. The RSD of glucose, maltose and maltotriose was 2.08%, 2.41% and 2.61%, respectively. And the recovery of glucose, maltose and maltotriose was 101.3%, 98.4% and 93.5%. It was credible to separate sugars from hydrolysates. The method is important for improving the inducible enzymes activity.

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Ichikawa, Takanori, Mizuki Tanaka, Takayasu Watanabe, Sitong Zhan, Akira Watanabe, Takahiro Shintani e Katsuya Gomi. "Crucial role of the intracellular α-glucosidase MalT in the activation of the transcription factor AmyR essential for amylolytic gene expression in Aspergillus oryzae". Bioscience, Biotechnology, and Biochemistry 85, n.º 9 (10 de julho de 2021): 2076–83. http://dx.doi.org/10.1093/bbb/zbab125.

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ABSTRACT We examined the role of the intracellular α-glucosidase gene malT, which is part of the maltose-utilizing cluster (MAL cluster) together with malR and malP, in amylolytic gene expression in Aspergillus oryzae. malT disruption severely affected fungal growth on medium containing maltose or starch. Furthermore, the transcription level of the α-amylase gene was significantly reduced by malT disruption. Given that the transcription factor AmyR responsible for amylolytic gene expression is activated by isomaltose converted from maltose incorporated into the cells, MalT may have transglycosylation activity that converts maltose to isomaltose. Indeed, transglycosylated products such as isomaltose/maltotriose and panose were generated from the substrate maltose by MalT purified from a malT-overexpressing strain. The results of this study, taken together, suggests that MalT plays a pivotal role in AmyR activation via its transglycosylation activity that converts maltose to the physiological inducer isomaltose.

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JHA, PRIYAMVADA, VINEET KUMAR, ANITA RANI e ANIL KUMAR. "Mapping QTLs controlling the biosynthesis of maltose in soybean". Romanian Biotechnological Letters 26, n.º 5 (20 de setembro de 2021): 2936–41. http://dx.doi.org/10.25083/rbl/26.5/2936.2941.

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The present study was carried out to identify genomic regions associated with maltose in 2 F2 populations through assessment of sugars using HPLC and genotyping using SSR markers across the genome. SSR markers, Sat_216 (chr 12) and Satt681 (chr 6) in F2 population I and Sat_105 (chr 20) in F2 population II showed significant (P< 0.5) association with maltose content through single marker analysis (SMA) with LOD score of 3.18 (R2 =9.7), 2.54 (R2 =6.8), and 3.54 (R2 =10.4), respectively. Composite interval mapping analysis (CIM) let to identify different QTLs (other than SMA) for maltose content on chr 11, chr 13 and chr 17 in F2 population I while chr 6 and chr15 in F2 population II. QTLs identified for maltose content are in proximity of known functional genes responsible for degradation of starch into maltose. QTLs identified for maltose in the study may be deployed for improving efficiency of marker assisted breeding for development of soybean genotypes with high levels of this sugar.

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MD (AYU), Dr B. S. Savadi. "ESTIMATION OF TOTAL MALTOSE CONTENT BY DNS METHOD IN VIDARIKAND (PUERARIA TUBEROSA)". Avishkara 01, n.º 03 (2022): 07–10. http://dx.doi.org/10.56804/avishkara.2022.1303.

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Background: Vidarikand (Pueraria tuberosa DC) is commonly known as Indian kudzu. Bhavaprakash mention the Vidarikand in its Guduchyadi varga they mention the synonyms of Vidarikandas, Swdukanda, Krostri, Sita, Ikshugandha, Kshirvalli, Kshirshukla, Payasvani. Chemical Constituents Tubers contain 85.1% dry matter, 64.6% carbohydrates, 28.4% crude fibres, 10.9% protein, 0.5% ether extract, vidarikand is rich carbohydrates and etc. Objective: The objective of the present study was to determine the total maltose content in Vidarikand (Pueraria tuberosa). Materials & Methods: The total maltose content in different concentration was estimated spectrophotometrically by DNS method. Results: The results showed that root of Vidarikanda (Puerariatuberosa) are rich source of Carbohydrates. The root extract of Vidarikanda in different concentration showed 10.15% of maltose for 2 gm of extract, and 26.45% of maltose in 4gm of extract. Conclusion: The total maltose content of Vidarikanda was well established by spectrophotometric studies. The estimation of total maltose was done for the first time which can be used for further chemical and biological studies.

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Humaira, Adinda, e Suseno Amien. "INDUKSI KALUS LIMA KULTIVAR SELEDRI (Apium graveolens L.) DENGAN SUKROSA DAN BERBAGAI KONSENTRASI MALTOSA". Agrin 23, n.º 1 (23 de novembro de 2019): 1. http://dx.doi.org/10.20884/1.agrin.2019.23.1.413.

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Penelitian ini bertujuan untuk mengetahui respon berbagai kultivar seledri terhadap induk sikalus dengan menggunakan sukrosa dan maltosa. Percobaan dilaksanakan dengan menggunakan Rancangan Acak Lengkap (RAL) pola faktorial yang terdiri atas dua faktor dan diulang tiga kali. Faktor pertama adalah kultivar seledri terdiri atas lima taraf yaitu Aroma, Bamby, Samantha, Sunda,Tall Utah. Faktor kedua adalah konsentrasi karbohidrat yang terdiri atas lima taraf yaitu sukrosa 20 g/L, maltosa 20 g/L), maltosa 30 g/L, maltosa 40 g/L, maltosa 60 g/L. Variabel yang diamati meliputi waktu awal kalus terbentuk, diameter kalus, warna kalus, tekstur kalus, kalus embriogenik, dan jumlah tunas pada tahap regenerasi. Hasil penelitian menunjukkan konsentrasi sukrosa 20 g/L merupakan konsentrasi terbaik terhadap kecepatan muncul kalus pada kultivar Bamby. Sukrosa 20 g/L memberikan pengaruh paling baik terhadap ukuran kalus pada kultivar Aroma. Maltosa 30 g/L mampu menginduksi kalus dari semua kultivar seledri yang digunakan. Kulvivar Samantha responsif terhadap pembentukan kalus di semua konsentrasi Maltosa yang digunakan. Kata kunci: seledri, sukrosa, maltosa, kalus Keywords: Celery, Plant Breeding, Carbohydrate, Maltose, and Callus

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Hollander, Robert C. "Recognizing Maltose-induced Hyponatremia". Annals of Internal Medicine 120, n.º 3 (1 de fevereiro de 1994): 248. http://dx.doi.org/10.7326/0003-4819-120-3-199402010-00018.

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47

Palevsky, Paul M. "Recognizing Maltose-induced Hyponatremia". Annals of Internal Medicine 120, n.º 3 (1 de fevereiro de 1994): 248. http://dx.doi.org/10.7326/0003-4819-120-3-199402010-00019.

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Ehrmann, Michael, Rainer Ehrle, Eckhard Hofmann, Winfried Boos e Andreas Schlösser. "The ABC maltose transporter". Molecular Microbiology 29, n.º 3 (agosto de 1998): 685–94. http://dx.doi.org/10.1046/j.1365-2958.1998.00915.x.

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Karzis, Joanne, Inge-Marié Petzer, Edward F. Donkin, Vinny Naidoo e Eric M. C. Etter. "Surveillance of Antibiotic Resistance of Maltose-Negative Staphylococcus aureus in South African Dairy Herds". Antibiotics 9, n.º 9 (18 de setembro de 2020): 616. http://dx.doi.org/10.3390/antibiotics9090616.

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Antibiotic resistance has been reported since the 1940s in both human and veterinary medicine. Many years of monitoring milk samples in South Africa led to identification of a novel maltose-negative Staphylococcus aureus (S. aureus) strain, which appears to be an emerging pathogen. In this study, the susceptibility of this strain to antibiotics was evaluated over time, during diverse seasons in various provinces and according to somatic cell count (SCC) categories. A data set of 271 maltose-negative S. aureus isolates, from milk samples of 117 dairy herds, was examined using the disk diffusion method, between 2010 and 2017. This study also compared the susceptibility testing of 57 maltose-negative and 57 maltose-positive S. aureus isolated from 38 farms, from three provinces using minimum inhibitory concentration (MIC). The MIC results for the maltose-negative S. aureus isolates showed highest resistance to ampicillin (100%) and penicillin (47.4) and lowest resistance (1.8%) to azithromycin, ciprofloxacin and erythromycin. The maltose-negative S. aureus isolates showed overall significantly increased antibiotic resistance compared to the maltose-positive strains, as well as multidrug resistance. Producers and veterinarians should consider probability of cure of such organisms (seemingly non-chronic) when adapting management and treatment, preventing unnecessary culling.

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Van Leeuwen, C. C. M., R. A. Weusthuis, E. Postma, P. J. A. Van den Broek e J. P. Van Dijken. "Maltose/proton co-transport in Saccharomyces cerevisiae. Comparative study with cells and plasma membrane vesicles". Biochemical Journal 284, n.º 2 (1 de junho de 1992): 441–45. http://dx.doi.org/10.1042/bj2840441.

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Maltose/proton co-transport was studied in intact cells and in plasma membrane vesicles of the yeast Saccharomyces cerevisiae. In order to determine uphill transport in vesicles, plasma membranes were fused with proteoliposomes containing cytochrome c oxidase as a proton-motive force-generating system. Maltose accumulation, dependent on the electrical and pH gradients, was observed. The initial uptake velocity and accumulation ratio in vesicles proved to be dependent on the external pH. Moreover, kinetic analysis of maltose transport showed that Vmax. values greatly decreased with increasing pH, whereas the Km remained virtually constant. These observations were in good agreement with results obtained with intact cells, and suggest that proton binding to the carrier proceeds with an apparent pK of 5.7. The observation with intact cells that maltose is co-transported with protons in a one-to-one stoichiometry was ascertained in the vesicle system by measuring the balance between proton-motive force and the chemical maltose gradient. These results show that maltose transport in vesicles prepared by fusion of plasma membranes with cytochrome c oxidase proteoliposomes behaves in a similar way as in intact cells. It is therefore concluded that this vesicle model system offers a wide range of new possibilities for the study of maltose/proton co-transport in more detail.

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