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Journal articles on the topic 'Structure and Prototropy'

Author: Grafiati

Published: 6 September 2023

Last updated: 19 July 2025

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1

Cornejo, J., and M. C. Hermosin. "Structural alteration of sepiolite by dry grinding." Clay Minerals 23, no. 4 (1988): 391–98. http://dx.doi.org/10.1180/claymin.1988.023.4.06.

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AbstractThe effects of dry grinding on the structure of sepiolite were studied by XRD, surface area measurement, TG-DTA and IR spectroscopy techniques. The results show that the sepiolite framework is rather resistant to mechanical stress and its alteration by dry grinding occurs through three successive, overlapping processes: (i) thinning of the fibrous particles without structural alteration; (ii) distortion of the parallel units of sepiolite fibres, affecting essentially the particle surface which transforms into an amorphous protective coating; (iii) disruption of the inner structure and

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2

Sheshashena Reddy, T., N. Rameshwar, B. Bhudevi, and A. Ram Reddy. "Structure dependent prototropy in 4-hydroxy-3-formylideneamino-1-methyl/phenylquinolin-2-ones." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 73, no. 5 (2009): 916–21. http://dx.doi.org/10.1016/j.saa.2009.04.019.

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3

Grigg, Ronald, Jasothara Markandu, Trevor Perrior, Sivagnanasundram Surendrakumar, and William J. Warnock. "Effect of structure on tandem 1,2-prototropy-cycloaddition versus tandem cyclisation-cycloaddition reactions of oximes." Tetrahedron Letters 31, no. 4 (1990): 559–62. http://dx.doi.org/10.1016/0040-4039(90)87034-w.

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4

Colsch, Benoit, Annelaure Damont, Christophe Junot, François Fenaille, and Jean-Claude Tabet. "Experimental evidence that electrospray-produced sodiated lysophosphatidyl ester structures exist essentially as protonated salts." European Journal of Mass Spectrometry 25, no. 3 (2019): 333–38. http://dx.doi.org/10.1177/1469066719838924.

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Sodiated lysoglycerophosphatidylethanolamine (LGPE) and lysoglycerophosphatidylcholine (LGPC) species dissociate under low collision energy by covalent bond cleavage resulting in product ions with either sodium retention or without sodium retention. For explaining these fragmentations, sodium chelation by heteroatoms (as charge-solvated structures) is often considered, and consequently, under keV collision conditions, sodium is “spectator” of cleavages (charge remote fragmentation). However, cleavage of such charge-solvated forms under low-energy conditions should result in sodium desolvation

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5

Perrin, Monique, Alain Thozet, Pilar Cabildo, Rosa Ma Claramunt, Eduard Valenti, and José Elguero. "Molecular structure and tautomerism of 3,5-bis(4-methylpyrazol-1-yl)-4-methylpyrazole." Canadian Journal of Chemistry 71, no. 9 (1993): 1443–49. http://dx.doi.org/10.1139/v93-186.

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The title compound C12N6H14, 1, crystallizes in the space group P21/n (a = 8.222(2) Å, b = 27.336(8) Å, c = 5.574(2) Å, α = 90.00°, β = 100.97(4)°, γ = 90.00°), Z = 4, d = 1.308 g cm−3. The conformation about the N—C bonds linking the pyrazole rings can be defined as EZ, with "pyridine-like" nitrogen atoms in an anti disposition [Formula: see text] and "pyridine-like" and "pyrrole-like" nitrogen atoms in a syn disposition [Formula: see text] with regard to the central pyrazole. Intermolecular hydrogen bonds between the central and the terminal pyrazole ring of configuration Z form centrosymmet

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6

Star, Alexander, Israel Goldberg, and Benzion Fuchs. "Diazadioxadecalin and salen podands and macrocycles within dynamic combinatorial virtual libraries: structure, prototropy, complexation and enantioselective catalysis." Journal of Organometallic Chemistry 630, no. 1 (2001): 67–77. http://dx.doi.org/10.1016/s0022-328x(01)00882-8.

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7

Szymańska, Małgorzata, and Irena Majerz. "Prototropy, Intramolecular Interactions, Electron Delocalization, and Physicochemical Properties of 1,8-dihydroxy-9-anthrone—DFT-D3 Study of Substituent Effects." Molecules 28, no. 1 (2023): 344. http://dx.doi.org/10.3390/molecules28010344.

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1,8-dihydroxy-9-anthrone are tricyclic compounds with a ketone group in the middle ring and two hydroxyl groups substituted in the side-aromatic rings what results in formation of two intramolecular hydrogen bonds in which the oxygen atom from the ketone group is the proton acceptor. 1,8-dihydroxy-9-anthrones in which intramolecular proton transfer between C10 and CO in the middle ring occurs, can exist in a tautomeric keto-enol equilibrium. For anthralin, the most important representative of this group, this equilibrium has been studied previously, but it has not been studied for its derivati

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8

Raczyńska, Ewa Daniela. "On Some Origins of Tautomeric Preferences in Neutral Creatinine in Vacuo: Search for Analogies and Differences in Cyclic Azoles and Azines." Symmetry 16, no. 1 (2024): 98. http://dx.doi.org/10.3390/sym16010098.

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In order to look for the origins of tautomeric preferences in neutral creatinine in vacuo, we examined prototropic conversions for model azoles, namely mono-hydroxy and mono-amino imidazoles, and also for their selected 1-methyl derivatives. All possible isomeric forms of creatinine and model compounds, resulting from intramolecular proton transfer (prototropy), conformational isomerism about –OH, and configurational isomerism about =NH, were studied in the gas phase (model of non-polar environment) by means of quantum-chemical methods. Because the bond-length alternation is a consequence of t

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9

Elbrus Mammadov, Sevinj Guliyeva, Elbrus Mammadov, Sevinj Guliyeva. "UNUSUAL TRANSFORMATIONS OF 2,3- AND 1,3- BUTHANEDIOL MONOPROPARGYL ETHERS." PAHTEI-Procedings of Azerbaijan High Technical Educational Institutions 46, no. 11 (2024): 94–102. https://doi.org/10.36962/pahtei46112024-11.

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Research in the field of chemistry of oxygen-containing derivatives of acetylene has acquired considerable interest. Of the simple ethers containing a triple carbon-carbon bond, ethynyl and propargyl ethers of monohydric alcohols and phenols, as well as alkyl and aryl ethers of acetylene glycols have been studied in most detail. Alkynyl, especially propargyl mono- and diesters of polyhydric alcohols have not been studied extensively. Due to the presence of highly reactive centers, ethers occupy a special place in the field of chemistry of oxygen-containing derivatives of acetylenes. Acetylene

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10

Lacalli, T. C. "Prototroch structure and innervation in the trochophore larva of Phyllodoce (Polychaeta)." Canadian Journal of Zoology 64, no. 1 (1986): 176–84. http://dx.doi.org/10.1139/z86-028.

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The prototroch and prototroch nerve in trochophores of two Phyllodoce species are described at the ultrastructural level and interpreted with reference to the observed normal behavior of larvae during swimming. The prototroch is a complex structure consisting of four tiers of cells of which the second bears the main locomotory cilia. Cells in the other tiers also have cilia but are notable chiefly for the slender processes they send to the prototroch nerve and which evidently contribute to the sheath that surrounds the nerve. Neurociliary synapses were not observed, but the prototroch arrests

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11

Raczyńska, Ewa Daniela, Pierre-Charles Maria, and Jean-François Gal. "Quantum Chemical Studies on the Prototropic and Acid/Base Equilibria for 2-Aminopyrrole in Vacuo—Role of CH Tautomers in the Design of Strong Brønsted Imino N-Bases." Molecules 30, no. 10 (2025): 2112. https://doi.org/10.3390/molecules30102112.

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In the quest of the pivotal origin of the very strong gas-phase proton basicity for some iminopyrrole derivatives, proposed in the literature on the basis of quantum chemical calculations, the full tautomeric and acid/base equilibria were investigated in vacuo for 2-aminopyrrole exhibiting enamino–imino tautomerism. Thermochemistry of these processes investigated at the Density Functional Theory (DFT) level indicates a lower stability for the imino than for the enamino tautomers. However, the imino N atom in the imino forms displays an exceptionally high basicity, particularly in the minor and

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12

Ma, Jiani, Jan-Michael Mewes, Kyle T. Harris, Timothy M. Dore, David Lee Phillips, and Andreas Dreuw. "Unravelling the early photochemical behavior of (8-substituted-7-hydroxyquinolinyl)methyl acetates through electronic structure theory and ultrafast transient absorption spectroscopy." Physical Chemistry Chemical Physics 19, no. 2 (2017): 1089–96. http://dx.doi.org/10.1039/c6cp05499d.

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13

Sergienko, V. S., V. L. Abramenko, and Yu E. Gorbunova. "Prototropic Tautomerism of Salicylideneimines. Crystal Structure of 3,5-Dichlorosalicylideneallylimine." Crystallography Reports 65, no. 1 (2020): 53–55. http://dx.doi.org/10.1134/s106377452001023x.

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14

Vouffo, Erik Donfack, Clovis Douanla-Meli, Angelbert Fusi Awantu, et al. "New Metabolites From the Endophytic Fungus Cercophora samala Associated With Mitragyna inermis." Natural Product Communications 16, no. 5 (2021): 1934578X2110132. http://dx.doi.org/10.1177/1934578x211013220.

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Two new natural products, mitrafungidione (1) elucidated as prototrop-isomers of ( R-3-acetyl-5-ethyl-4-hydroxy-5 H-furan-2-one, and maristachone F (2a), elucidated as 5-(1-hydroxyethyl)-4-(hydroxymethyl)-3-methoxy-2-methylphenol, together with 5 known compounds have been isolated from the solid cultures of an endophytic fungus associated with Mitragyna inermis (Rubiaceae) and identified as Cercophora samala. The structures of these compounds were elucidated by detailed spectroscopic analysis and by comparison of their spectroscopic data with those reported in the literature. The absolute conf

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15

Radeglia, Reiner, Jörg Andersch, and Werner Schroth. "Zum dynamischen Strukturverhalten des Dimethylamin—Kohlendioxid-Komplexes (Dimcarb) / On the Dynamic Structure Behaviour of the Dimethylamine—Carbondioxide Complex (Dimcarb)." Zeitschrift für Naturforschung B 44, no. 2 (1989): 181–86. http://dx.doi.org/10.1515/znb-1989-0215.

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Abstract Dimcarb, a liquid distillable 1 .8 :1-dimethylamine-carbondioxide complex which can be used as a preparatively profitable dimethylamine source, displays unusual properties in view of a salt ("dimethylammonium dimethylcarbamate"). The dynamic structure behaviour has been investigated by1'H, 13C, and 15N NMR spectroscopy: At ambient temperature dimcarb underlies a rapid dimethylamine change between ammonium and carbamate functionality (⊿G ≠ about 58 kJ/mol). On further temperature decreasing prototropic interactions between dimethylammonium and dimethylamine as well as dimethylcarbamate

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16

Kubicki, Maciej. "Two tautomers in one crystal: 4(5)-nitro-5(4)-methoxyimidazole." Acta Crystallographica Section B Structural Science 60, no. 2 (2004): 191–96. http://dx.doi.org/10.1107/s0108768104003179.

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The case of prototropic annular tautomerism in an imidazole derivative has been found. The crystal structure contains a 50:50 mixture of two tautomers: 4-nitro-5-methoxyimidazole and 5-nitro-4-methoxyimidazole. The X-ray experiment actually shows the superposition of these compounds; it appears as if the structure is centrosymmetric and the N—H hydrogen atoms are disordered over two ring N atoms. Owing to the hydrogen-bond pattern, the values of their site occupation factors have to be exactly equal to 1/2. The molecules are connected into a three-dimensional network by means of N—H...N and C—

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17

Fain, V. Ya, B. E. Zaitsev та M. A. Ryabov. "1,10-quinoid structure and prototropic amino-imine tautomerism of α-aminoanthraquinones". Russian Journal of General Chemistry 82, № 9 (2012): 1558–66. http://dx.doi.org/10.1134/s1070363212090186.

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18

Szabo, Jan, and Gerhard Maas. "Derivatives of the Triaminoguanidinium Ion, 2. Prototropic Tautomerism, Crystal and Molecular Structure of N,N´,N´´-Tris(propan- 2-iminyl)guanidine [1, 2]." Zeitschrift für Naturforschung B 68, no. 3 (2013): 207–13. http://dx.doi.org/10.5560/znb.2013-3023.

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The title compound, C10H20N6 (2), was prepared from N,N´,N´´-triaminoguanidinium chloride. Solvent- and temperature-dependent 1H NMR spectra indicating prototropic tautomerism were observed in solution. The crystal and molecular structure was determined by X-ray diffraction analysis. The compound crystallizes in the hexagonal space group P63/m. The molecules lie on crystallographic mirror planes parallel to the a,b plane, which are separated from each other by 3:37 Å . The threefold crystallographic symmetry of the molecules is due to disorder with positional averaging of individual molecules.

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19

Jameh-Bozorghi, Saeed, Zahra Javanshir, and D. Nori Shargh. "Prototropic and metallotropic migration of isolobal fragments on indol rings. Theoretical study and NBO analysis." JOURNAL OF ADVANCES IN CHEMISTRY 5, no. 1 (2009): 614–25. http://dx.doi.org/10.24297/jac.v5i1.942.

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Molecular structures, energies, NBO analysis and sigmatropic behaviour of 1-Indenyl(dihydro)borane (1) and 1-Indenyl-threecarbonylcobalt(I) (2) were investigated using DFT and ab initio molecular orbital methods. In these compounds BH2 and Co(CO)3 fragments areisolobal. The Results of calculations using B3LYP, HF and MP2methods [Basis set 6-311+G**] showed that -BH2 and -Co(CO)3 had similar behaviour in sigmatropic shifts. Prototropic shifts in compounds 1 and 2 have similar mechanisms too. Results showed that metallotrotropic shift is faster than Prototrpic shift in compounds 1 and 2. The act

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20

Markova, M. V., I. V. Tatarinova, O. A. Tarasova, K. A. Apatrsin, V. V. Kireeva, and B. A. Trofimov. "Cationic copolymerisation of cholesterol vinyl ether with N-allenylpyrrolidone; a route to pharmacologically promising oligomers." Доклады Академии наук 485, no. 6 (2019): 697–700. http://dx.doi.org/10.31857/s0869-56524856697-700.

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Cationic copolymerization of cholesterol vinyl ether with N-allenylpyrrolidone yielded co-oligomers with molecular mass of 1200-2100. The polymerization of N-allenylpyrrolidone involves both 1,2- and 2,3-positions of the allenyl substituent to give four types of units as a result of prototropic isomerization of the initially formed structures. In the developed method, the composition of co-oligomers can be controlled and, hence, their hydrophilic/hydrophobic balance, solubility, and membranotropic properties can also be controlled to change the potential biological activity of the products.

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21

Ashniev, German A., Sergey N. Petrov, Stanislav N. Iablokov, and Dmitry A. Rodionov. "Genomics-Based Reconstruction and Predictive Profiling of Amino Acid Biosynthesis in the Human Gut Microbiome." Microorganisms 10, no. 4 (2022): 740. http://dx.doi.org/10.3390/microorganisms10040740.

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The human gut microbiota (HGM) have an impact on host health and disease. Amino acids are building blocks of proteins and peptides, also serving as precursors of many essential metabolites including nucleotides, cofactors, etc. Many HGM community members are unable to synthesize some amino acids (auxotrophs), while other members possess complete biosynthetic pathways for these nutrients (prototrophs). Metabolite exchange between auxotrophs and prototrophs affects microbial community structure. Previous studies of amino acid biosynthetic phenotypes were limited to model species or narrow taxono

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22

Secrieru, Alina, Susy Lopes, Maria L. S. Cristiano, and Rui Fausto. "Structure and IR Spectra of 3(5)-Aminopyrazoles and UV-Induced Tautomerization in Argon Matrix." Molecules 26, no. 14 (2021): 4299. http://dx.doi.org/10.3390/molecules26144299.

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The prototropic tautomerism in 3(5)-aminopyrazoles was investigated by matrix isolation infrared (IR) spectroscopy, supported by DFT(B3LYP)/6-311++G(d,p) calculations. In consonance with the experimental data, the calculations predict tautomer 3-aminopyrazole (3AP) to be more stable than the 5-aminopyrazole (5AP) tautomer (calculated energy difference: 10.7 kJ mol−1; Gibbs free energy difference: 9.8 kJ mol−1). The obtained matrix isolation IR spectra (in both argon and xenon matrices) were interpreted, and the observed bands were assigned to the tautomeric forms with help of vibrational calcu

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23

Nikitina, Polina A., Tatiana Yu Koldaeva, Vitaly S. Mityanov, Vladimir S. Miroshnikov, Elizaveta I. Basanova, and Valery P. Perevalov. "Prototropic Tautomerism and Some Features of the IR Spectra of 2-(3-Chromenyl)-1-hydroxyimidazoles." Australian Journal of Chemistry 72, no. 9 (2019): 699. http://dx.doi.org/10.1071/ch19222.

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Prototropic tautomerism of 2-(3-chromenyl)-1-hydroxyimidazoles with various substituents in the chromenyl moiety (1-hydroxyimidazole – imidazole N-oxide) was studied by means of 1H NMR and IR spectroscopies. It was demonstrated that in d6-DMSO solution, the substituents in the chromenyl ring have no influence on the equilibrium shift: the prevalence of the N-oxide tautomeric form is caused by the possibility of stabilization of the planar structure with the help of the carbonyl group in position 5 of the imidazole ring. In contrast, in the solid state the general effect of the chromenyl substi

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24

Kühn, Christiane, R. Beckert, U. W. Grummt, C. Käpplinger, and E. Birckner. "1,4,5,8-Tetraazafulvalene – Darstellung schwefelhaltiger Derivate und Zuordnung des Chromophors / 1,4,5,8-Tetraazafulvalenes – Synthesis of Sulfur-Containing Derivatives and Classification of the Chromophor." Zeitschrift für Naturforschung B 59, no. 4 (2004): 406–13. http://dx.doi.org/10.1515/znb-2004-0408.

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Abstract In order to obtain sulfur-containing tetraazafulvalenes the derivatives 1 - 3 were cross-coupled with different types of acetylenes via palladium-catalyzed reactions. Starting from the tetrabromoaryl derivative 3a, four bromine atoms could be replaced by 2-ethynylthiophene. Under analogous conditions, the methylsulfanyl esters 7 -11 could be obtained by employing 4-ethynylbenzoic acid 4-(methylsulfanyl)butylester 6. Lipoic acid could be integrated into tetraazafulvalenes successfully in a two step reaction. First, the Sonogashira coupling method yielded the compound 12 possessing two

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25

Szemik-Hojniak, A., T. Glowiak, I. Deperasinska, and A. Puszko. "Crystal structure and spectral considerations of 5-methyl-2-nitraminopyridine N-oxide." Canadian Journal of Chemistry 80, no. 9 (2002): 1242–51. http://dx.doi.org/10.1139/v02-142.

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The crystal structure of 5-methyl-2-nitraminopyridine N-oxide (5M) has been determined and its electronic absorption spectra in the solution have been investigated. In the solid, two monomeric proton-transferred (PT) units of 5M are perpendicularly located in the crystal lattice. They are connected by two intermolecular hydrogen bonds of different strength (O-H···N 2.647(3) and 2.695(3) Å). In the gas phase the same relative arrangement of both 5M (PT) monomers has been found. As results from semiempirical PM3-CI calculations (1214), the prototropic amino (H) [Formula: see text] imino (PT) eq

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26

O'Connell, K. F., Y. Surdin-Kerjan, and R. E. Baker. "Role of the Saccharomyces cerevisiae general regulatory factor CP1 in methionine biosynthetic gene transcription." Molecular and Cellular Biology 15, no. 4 (1995): 1879–88. http://dx.doi.org/10.1128/mcb.15.4.1879.

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Saccharomyces cerevisiae general regulatory factor CP1 (encoded by the gene CEP1) is required for optimal chromosome segregation and methionine prototrophy. MET16-CYC1-lacZ reporter constructs were used to show that MET16 5'-flanking DNA contains a CP1-dependent upstream activation sequence (UAS). Activity of the UAS required an intact CP1-binding site, and the effects of cis-acting mutations on CP1 binding and UAS activity correlated. In most respects, MET16-CYC1-lacZ reporter gene expression mirrored that of chromosomal MET16; however, the endogenous gene was found to be activated in respons

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27

Zhang, Chong, Xiaohui Zhang, Zhengying Yao, Yaping Lu, Fengxia Lu, and Zhaoxin Lu. "A new method for multiple gene inactivations in Bacillus subtilis 168, producing a strain free of selectable markers." Canadian Journal of Microbiology 57, no. 5 (2011): 427–36. http://dx.doi.org/10.1139/w11-035.

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This study describes a novel method for repeated gene inactivation in Bacillus subtilis 168. A B. subtilis strain (BS-PS) that is conditionally auxotrophic for lysine was obtained by replacing the PlysA promoter with the Pspac promoter. The homologous recombination integration vector PLC-T was constructed to contain lacI, which encodes a Pspac promoter repressor, and the chloromycetin resistance gene. Target genes were manipulated by generating an insertion sequence with two homologous arms and the target gene in PLC-T to create a specific integrating vector. Integration into the BS-PS chromos

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28

Stewart, Ross, and S. J. Gumbley. "Synthesis, base strength, and prototropic behaviour of a number of alkyllumazines." Canadian Journal of Chemistry 63, no. 12 (1985): 3290–93. http://dx.doi.org/10.1139/v85-544.

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A number of lumazines and 5-deazalumazines containing a methyl group at C-7 have been prepared, their pKBH+ values determined, and measurements made of the rates at which the hydrogen atoms of their 7-methyl groups undergo isotopic exchange in aqueous sulfuric acid. The presence of an alkyl group at N-8 in the protonated forms of these compounds activates the neighbouring methyl group at C-7; the effect is considerably larger than that previously observed for a methyl group at C-6, which is the other neighbouring position. The comparison of methyl and hydrogen at N-8 can be made only for the a

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29

Sydorenko, Ivan, Serhii Holota, Andrii Lozynskyi, et al. "2-(Cyclopropylamino)-5-(4-methoxybenzylidene)thiazol-4(5H)-one." Molbank 2022, no. 4 (2022): M1478. http://dx.doi.org/10.3390/m1478.

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Multicomponent reactions effectively contribute to modern organic and medicinal chemistry. 4-Thiazolidinone core and cyclopropyl moiety are important structural motifs for design of potential biologically active molecules. In the present paper, the convenient step-economy and cost-effective synthesis of 2-(cyclopropylamino)-5-(4-methoxybenzylidene)thiazol-4(5H)-one (2) is described based on the application of the MCR methodology. The proposed approach includes direct one-pot interaction of 2-thioxothiazolidin-4-one (rhodanine), 4-methoxybenzaldehyde with cyclopropylamine which was used in 10%

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30

Amado, Patrícia S. M., Inês C. C. Costa, José A. Paixão, Ricardo F. Mendes, Sofia Cortes, and Maria L. S. Cristiano. "Synthesis, Structure and Antileishmanial Evaluation of Endoperoxide–Pyrazole Hybrids." Molecules 27, no. 17 (2022): 5401. http://dx.doi.org/10.3390/molecules27175401.

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Leishmaniases are among the most impacting neglected tropical diseases. In attempts to repurpose antimalarial drugs or candidates, it was found that selected 1,2,4-trioxanes, 1,2,4,5-tetraoxanes, and pyrazole-containing chemotypes demonstrated activity against Leishmania parasites. This study reports the synthesis and structure of trioxolane–pyrazole (OZ1, OZ2) and tetraoxane–pyrazole (T1, T2) hybrids obtained from the reaction of 3(5)-aminopyrazole with endoperoxide-containing building blocks. Interestingly, only the endocyclic amine of 3(5)-aminopyrazole was found to act as nucleophile for a

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31

Camorali, Sara, Loredana Leone, Laura Piscopo, and Lorenzo Tei. "Relaxivity Modulation of Gd-HPDO3A-like Complexes by Introducing Polar and Protic Peripheral Groups." Molecules 29, no. 19 (2024): 4663. http://dx.doi.org/10.3390/molecules29194663.

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In the last three decades, high-relaxivity Magnetic Resonance Imaging (MRI) contrast agents (CAs) have been intensively sought, aiming at a reduction in the clinically injected dose while maintaining the safety of the CA and obtaining the same pathological information. Thus, four new Gd(III) complexes based on modified 10-(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (HP-DO3A) macrocyclic structure were designed and synthesized by introducing further polar and protic functional groups (amides, phosphonates, and diols) adjacent to the metal-coordinated hydroxyl group. A

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32

Banks, G. R., and S. Y. Taylor. "Cloning of the PYR3 gene of Ustilago maydis and its use in DNA transformation." Molecular and Cellular Biology 8, no. 12 (1988): 5417–24. http://dx.doi.org/10.1128/mcb.8.12.5417-5424.1988.

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The Ustilago maydis PYR3 gene encoding dihydroorotase activity was cloned by direct complementation of Escherichia coli pyrC mutations. PYR3 transformants of E. coli pyrC mutants expressed homologous transcripts of a variety of sizes and regained dihydroorotase activity. PYR3 also complemented Saccharomyces cerevisiae ura4 mutations, and again multiple transcripts were expressed in transformants, and enzyme activity was regained. A 1.25-kilobase poly(rA)+ PYR3 transcript was detected in U. maydis itself. Linear DNA carrying the PYR3 gene transformed a U. maydis pyr3-1 pyrimidine auxotroph to p

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Banks, G. R., and S. Y. Taylor. "Cloning of the PYR3 gene of Ustilago maydis and its use in DNA transformation." Molecular and Cellular Biology 8, no. 12 (1988): 5417–24. http://dx.doi.org/10.1128/mcb.8.12.5417.

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The Ustilago maydis PYR3 gene encoding dihydroorotase activity was cloned by direct complementation of Escherichia coli pyrC mutations. PYR3 transformants of E. coli pyrC mutants expressed homologous transcripts of a variety of sizes and regained dihydroorotase activity. PYR3 also complemented Saccharomyces cerevisiae ura4 mutations, and again multiple transcripts were expressed in transformants, and enzyme activity was regained. A 1.25-kilobase poly(rA)+ PYR3 transcript was detected in U. maydis itself. Linear DNA carrying the PYR3 gene transformed a U. maydis pyr3-1 pyrimidine auxotroph to p

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Kosar Kirca, Basak, Gonca Ozdemir Tarı, Cıgdem Albayrak Kastas, Mustafa Odabasoglu, and Orhan Buyukgungor. "Crystal structure, spectral characterization, molecular modeling studies and structural effects of the proton transfer process for (E)-5-methoxy-2-[(3,4-dimethylphenylimino) methyl]phenol." Macedonian Journal of Chemistry and Chemical Engineering 36, no. 2 (2017): 265. http://dx.doi.org/10.20450/mjcce.2017.1295.

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The main purpose of this study is to characterize a new organic material, (E)-5-methoxy-2-[(3,4-dimethylphenylimino)methyl]phenol, which was synthesized and grown as a single crystal. The molecular structure and spectroscopic properties of the ortho-hydroxy Schiff base compound were determined by X-ray diffraction analysis, Fourier-transform infrared (FT-IR), ultraviolet-visible (UV-Vis) and nuclear magnetic resonance (NMR) spectroscopy techniques, experimentally and computationally with density functional theory (DFT) calculations. X-ray and UV-Vis studies show that the compound exists in an

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35

Okouchi, S., K. Yamanaka, Y. Ishihara, T. Yanaka, and H. Uedaira. "Relationship between water qualities and treatments in the ultra pure water production system." Water Science and Technology 30, no. 10 (1994): 237–41. http://dx.doi.org/10.2166/wst.1994.0533.

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In an ultra pure water (UPW) production system which can satisfy the water qualities for 4 megabit DRAM, the changes in water qualities from a tap water (58.4 mg/dm3 as CaCO3 hardness) as a raw water to UPW were followed from the view of the micro-structure and microdynamic behavior of water molecules with increasing of the water purity by a complex permittivity and 17O-NMR measurements, as well as measurements of resistivity, density, and so on. The dielectric relaxation time and spin-lattice relaxation time of 17O nuclei related to the microdynamic behavior of water molecules indicated a tra

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36

Sergienko, V. S., V. L. Abramenko, M. D. Surazhskaya, and A. V. Churakov. "Prototropic Tautomerism of o-Oxyazomethines. Crystal Structure of (E)-1-(((Pyridin-3-ylmethyl)iminio)methyl)naphthalen-2-olate." Crystallography Reports 68, no. 7 (2023): 1109–12. http://dx.doi.org/10.1134/s1063774523600382.

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37

Krishnamurthy, Mannam, Karthik A. Iyer, and Sneh K. Dogra. "Electronic structure of quinoxaline-2,3(1H,4H)dione and its prototropic species in the ground and excited singlet states." Journal of Photochemistry 38 (June 1987): 277–87. http://dx.doi.org/10.1016/0047-2670(87)87023-5.

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38

Shagun, V. A., V. F. Sidorkin, V. A. Usov, and M. G. Voronkov. "Quantum-chemical study of the structure and prototropic conversions of 2-methyl-1,3-bishetero derivatives of indene and indan." Bulletin of the Academy of Sciences of the USSR Division of Chemical Science 35, no. 5 (1986): 1019–22. http://dx.doi.org/10.1007/bf00955371.

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Barczak, A. J., J. Zhao, K. D. Pruitt, and R. L. Last. "5-Fluoroindole resistance identifies tryptophan synthase beta subunit mutants in Arabidopsis thaliana." Genetics 140, no. 1 (1995): 303–13. http://dx.doi.org/10.1093/genetics/140.1.303.

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Abstract A study of the biochemical genetics of the Arabidopsis thaliana tryptophan synthase beta subunit was initiated by characterization of mutants resistant to the inhibitor 5-fluoroindole. Thirteen recessive mutations were recovered that are allelic to trp2-1, a mutation in the more highly expressed of duplicate tryptophan synthase beta subunit genes (TSB1). Ten of these mutations (trp2-2 through trp2-11) cause a tryptophan requirement (auxotrophs), whereas three (trp2-100 through trp2-102) remain tryptophan prototrophs. The mutations cause a variety of changes in tryptophan synthase beta

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40

Brovarets’, Ol’ha O., and Dmytro M. Hovorun. "A new era of the prototropic tautomerism of the quercetin molecule: A QM/QTAIM computational advances." Journal of Biomolecular Structure and Dynamics 38, no. 16 (2019): 4774–800. http://dx.doi.org/10.1080/07391102.2019.1691660.

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41

Fedorova, A. A., O. V. Lefedova, and S. A. Shlykov. "Structure of 2-nitro-2’-hydroxy-5’-methylazobenzene: Theoretical and spectroscopic study." Fine Chemical Technologies 18, no. 4 (2023): 315–27. http://dx.doi.org/10.32362/2410-6593-2023-18-4-315-327315.

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Objectives. 2-Hydroxy-nitroazobenzenes comprise reagents for the synthesis of heteroaromatic compounds, in the molecules of which the benzene and azole cycles are annulated. These reagents are widely used in the production of chemical products for various industries. In particular, 2-2’-hydroxy-5’-methylphenylbenzotriazole is used as an effective photo stabilizer for polystyrene and polyethylene. A promising method for its preparation is the liquid-phase catalytic hydrogenation of 2-nitro-2'-hydroxy-5'-methylazobenzene (2NAB). The aim of the present study was to establish the structure of 2NAB

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42

Fedorova, A. A., O. V. Lefedova, and S. A. Shlykov. "Structure of 2-nitro-2’-hydroxy-5’-methylazobenzene: Theoretical and spectroscopic study." Fine Chemical Technologies 18, no. 4 (2023): 315–27. http://dx.doi.org/10.32362/2410-6593-2023-18-4-315-327.

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Objectives. 2-Hydroxy-nitroazobenzenes comprise reagents for the synthesis of heteroaromatic compounds, in the molecules of which the benzene and azole cycles are annulated. These reagents are widely used in the production of chemical products for various industries. In particular, 2-2’-hydroxy-5’-methylphenylbenzotriazole is used as an effective photo stabilizer for polystyrene and polyethylene. A promising method for its preparation is the liquid-phase catalytic hydrogenation of 2-nitro-2'-hydroxy-5'-methylazobenzene (2NAB). The aim of the present study was to establish the structure of 2NAB

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43

Rak, Janusz, Jerzy Blazejowski, and Randy J. Zauhar. "Theoretical studies on the prototropic tautomerism, structure, and features of acridine and 9-acridinamine free bases and their protonated forms." Journal of Organic Chemistry 57, no. 13 (1992): 3720–25. http://dx.doi.org/10.1021/jo00039a039.

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44

Fofanova, Elizaveta. "Dimorphilus gyrociliatus (Annelida: Dinophiliformia) Dwarf Male Nervous System Represents a Common Pattern for Lophotrochozoa." Biology 11, no. 11 (2022): 1674. http://dx.doi.org/10.3390/biology11111674.

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Dinophiliformia is a newly revealed clade within Annelida that is a sister group to Pleistoannelida. Dimorphilus gyrociliatus is a representative of this clade that has fascinated scientists with its high degree of sexual dimorphism. Both males and females are small, worm-like creatures that have specific ciliary structures: anterior ventral, posterior ventral, and dorsal ciliary fields in males, and prototroch, metatroch, and ventral ciliary fields in females. There are data on the morphology and development of the nervous system in Oweniidae, Sipunculida, Pleistoannelida, and even Dinophilif

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Strathmann, Richard R. "Multiple origins of feeding head larvae by the Early Cambrian." Canadian Journal of Zoology 98, no. 12 (2020): 761–76. http://dx.doi.org/10.1139/cjz-2019-0284.

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In many animals the head develops early, most of the body axis later. A larva composed mostly of the developing front end therefore can attain mobility and feeding earlier in development. Fossils, functional morphology, and inferred homologies indicate that feeding head larvae existed by the Early Cambrian in members of three major clades of animals: ecdysozoans, lophotrochozoans, and deuterostomes. Some of these early larval feeding mechanisms were also those of juveniles and adults (the lophophore of brachiopod larvae and possibly the ciliary band of the dipleurula of hemichordates and echin

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Nori-Shargh, Davood, Hossein Aghabozorgh, Karim Zare, Mohammad Reza Talei, Bavil Olyai, and Saeed Jameh-Bozorghi. "Ab Initio Study of Structures, Metallotropic 1,2-Shifts and Prototropic 1,2-Shifts of Cyclopentadienyl(trimethyl)silane, -germane and -stannane." Phosphorus, Sulfur, and Silicon and the Related Elements 178, no. 2 (2003): 341–51. http://dx.doi.org/10.1080/10426500307946.

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Griffiths, A. J. F., X. Yang, F. J. Debets, and Y. Wei. "Plasmids in natural populations of Neurospora." Canadian Journal of Botany 73, S1 (1995): 186–92. http://dx.doi.org/10.1139/b95-244.

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Eukaryotic plasmids are mainly fungal. Global Neurospora populations have been surveyed and show that approximately half the isolates have one or more plasmids. There are distinct homology groups of plasmids and most groups are distributed across species. One example is also in a related genus, Gelasinospora. Most plasmids are apparently benign but several examples are virulent, killing by insertion into mtDNA. In Hawaii, one of the virulent plasmids, kalilo, might be increasing in frequency. Plasmids can be transmitted horizontally between laboratory strains by forced heterokaryosis or by tra

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48

Halcrow, M. A., H. R. Powell, and M. J. Duer. "Tautomerism in 3{5}-(dimethoxyphenyl)pyrazoles." Acta Crystallographica Section B Structural Science 52, no. 4 (1996): 746–52. http://dx.doi.org/10.1107/s0108768196005204.

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The single-crystal X-ray structures of 3{5}-(2′,5′-dimethoxyphenyl)pyrazole (HI) and the hemihydrate of 3 {5}-(3/,4′-dimethoxyphenyl)pyrazole (IV) have been determined. Compound (HI) exists purely as the 5-substituted prototropomer in the crystal; the pyrazole pyrollic N—H proton is involved in a three-way hydrogen bond, involving an intramolecular contact with a methoxy oxygen donor and an intermolecular interaction to the pyridinic N atom of a neighbouring molecule, forming discrete hydrogen-bonded dimers. There is no evidence of degenerate proton transfer within the dimeric units from CPMAS

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49

Wollesen, Tim, Sonia Victoria Rodríguez Monje, André Luiz de Oliveira, and Andreas Wanninger. "Staggered Hox expression is more widespread among molluscs than previously appreciated." Proceedings of the Royal Society B: Biological Sciences 285, no. 1888 (2018): 20181513. http://dx.doi.org/10.1098/rspb.2018.1513.

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Hox genes are expressed along the anterior–posterior body axis in a colinear fashion in the majority of bilaterians. Contrary to polyplacophorans, a group of aculiferan molluscs with conserved ancestral molluscan features, gastropods and cephalopods deviate from this pattern by expressing Hox genes in distinct morphological structures and not in a staggered fashion. Among conchiferans, scaphopods exhibit many similarities with gastropods, cephalopods and bivalves, however, the molecular developmental underpinnings of these similar traits remain unknown. We investigated Hox gene expression in d

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50

Chirkova, Zhanna V., Sergey I. Filimonov, and Igor G. Abramov. "SYNTHESIS OF BENZOFURAN-5,6-DICARBONITRILES ANNELATED WITH PYRAZOLE CYCLE." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 60, no. 6 (2017): 45. http://dx.doi.org/10.6060/tcct.2017606.5576.

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The principal method for the preparation of substituted 4-formyl-1H-pyrazoles was the treatment of hydrazones of different structure with Vilsmeier-Haack reagent. However, for the heterocyclic benzofuran system this reaction is rarely used. Synthetic methods for preparation of novel substituted 3-(4-fomyl-1H-pyrazole-3-yl)-2-methylbenzofuran-5,6-dicarbonitriles and 2-(1H-pyrazole-4-yl)-benzofuran-5,6-dicarbonitriles were developed by modification of 2,3-disubstituted benzofuran-5,6-dicarbonitriles via Vilsmeier-Haack reaction. New substituted 3-(4-fomyl-1H-pyrazole-3-yl)-2-methylbenzofuran-5,6

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