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A. V. Mashkina - One of the best experts on this subject based on the ideXlab platform.
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Catalytic Synthesis of Some Sulfur-containing Heterocyclic Compounds. (Review)
Chemistry of Heterocyclic Compounds, 2002Co-Authors: A. V. MashkinaAbstract:Researches on the synthesis of sulfur-containing heterocyclic compounds at the G. K. Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, are reviewed. They include the synthesis of Thiolane by the recyclization of THF in hydrogen sulfide; the synthesis thiacycloalkanes by the hydrogenation of thiophenes; the synthesis of 4-methylthiazole by the reaction of SO_2 with methylisopropylideneamine; the synthesis of thiophenes by the heterocyclization of aliphatic compounds of sulfur and dehydrogenation of thiacycloalkanes; the synthesis of Thiolane 1,1-dioxide by the hydrogenation of 2- and 3-thiolene 1,1-dioxides and 3-alkoxyThiolane 1,1-dioxides; the synthesis of sulfoxides by the oxidation of thiacycloalkanes with atmospheric oxygen.
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Catalytic Hydrogenation of Thiophene to Thiolane in the Gas Phase
Chemistry of Heterocyclic Compounds, 2001Co-Authors: A. V. Mashkina, L. G. SalakhtuevaAbstract:The hydrogenation of thiophene in the gas phase in the presence of palladium-sulfide catalyst leads to the production of Thiolane and hydrogenolysis products (butane and hydrogen sulfide), which are formed during the decomposition of the thiophene and Thiolane. The hydrogenation rate of thiophene increases with increase of its content in the reaction mixture and also with increase of the hydrogen pressure and is reduced by Thiolane. The yield of Thiolane calculated on the reacted thiophene is 70-90% with 30-60% conversion of the thiophene.
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Activity of transition metal sulfides in hydrogenation of thiolene-1,1-dioxides
Reaction Kinetics and Catalysis Letters, 1999Co-Authors: A. V. Mashkina, T. S. SukharevaAbstract:The activity and selectivity of sulfides of group VI–VIII metals in the liquid-phase hydrogenation of thiolene-1,1-dioxides were studied at elevated hydrogen pressure. The generation of Thiolane-1,1-dioxide is accompanied by the substrate decomposition, which is especially intensive for 3-thiolene-1,1-dioxide hydrogenation. These processes follow absolutely independent routes. The catalytic activity of sulfides in the generation of Thiolane-1,1-dioxide decreases in the following row: PdS>Rh_2S_3>Re_2S_7>OsS_2>PtS_2>CoOS>WS_2>RuS_2 >NiOS.
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catalytic hydrogenation of thiolene 1 1 dioxides to Thiolane 1 1 dioxide certain problems of the resistance of hydrogenation catalysts to sulfur
Russian Chemical Reviews, 1997Co-Authors: A. V. MashkinaAbstract:The state of research on the catalytic liquid-phase hydrogenation of 2- and 3-thiolene 1,1-dioxides to Thiolane 1,1-dioxide is analysed. Data on the activities and selectivities of Group VIII metals and their complexes and sulfides, both massive and supported, as well as the reaction conditions and hydrogenation mechanisms are considered. The causes of the deactivation of catalysts in the synthesis of Thiolane 1,1-dioxide and procedures for increasing their resistance to sulfur are described. Certain general problems of the resistance of hydrogenation catalysts to sulfur are discussed. The bibliography includes 130 references.
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Palladium activity in 3-thiolene-1,1-dioxide hydrogenation in the presence of alkalis
Reaction Kinetics and Catalysis Letters, 1997Co-Authors: A. V. Mashkina, V. N. Yakovleva, T. P. VoskresenskayaAbstract:Metallic palladium supported on γ-Al_2O_3 exhibits low activity in 3-thiolene-1,1-dioxide hydrogenation in alkaline alcohol solutions. It converts the above thiolene to 3-alkoxy-Thiolane-1,1-dioxide, which is hydrogenated to Thiolane-1,1-dioxide, at elevated temperatures favoring Pd sulfurization to PdS.
Rikkert K Wierenga - One of the best experts on this subject based on the ideXlab platform.
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Crystallographic substrate binding studies of Leishmania mexicana SCP2-thiolase (type-2): unique features of oxyanion hole-1.
Protein Engineering Design & Selection, 2017Co-Authors: Rajesh K Harijan, Tiila-riikka Kiema, Shahan M. Syed, Imran Qadir, Muriel Mazet, Frédéric Bringaud, Paul A M Michels, Rikkert K WierengaAbstract:Structures of the C123A variant of the dimeric Leishmania mexicana SCP2-thiolase (type-2) (Lm-thiolase), complexed with acetyl-CoA and acetoacetyl-CoA, respectively, are reported. The catalytic site of thiolase contains two oxyanion holes, OAH1 and OAH2, which are important for catalysis. The two structures reveal for the first time the hydrogen bond interactions of the CoA-thioester oxygen atom of the substrate with the hydrogen bond donors of OAH1 of a CHH-thiolase. The amino acid sequence fingerprints ( xS, EAF, G P) of three catalytic loops identify the active site geometry of the well-studied CNH-thiolases, whereas SCP2-thiolases (type-1, type-2) are classified as CHH-thiolases, having as corresponding fingerprints xS, DCF and G P. In all thiolases, OAH2 is formed by the main chain NH groups of two catalytic loops. In the well-studied CNH-thiolases, OAH1 is formed by a water (of the Wat-Asn(NEAF) dyad) and NE2 (of the GHP-histidine). In the two described liganded Lm-thiolase structures, it is seen that in this CHH-thiolase, OAH1 is formed by NE2 of His338 (HDCF) and His388 (GHP). Analysis of the OAH1 hydrogen bond networks suggests that the GHP-histidine is doubly protonated and positively charged in these complexes, whereas the HDCF histidine is neutral and singly protonated.
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structural characterization of a mitochondrial 3 ketoacyl coa t1 like thiolase from mycobacterium smegmatis
Acta Crystallographica Section D-biological Crystallography, 2015Co-Authors: Neelanjana Janardan, Rajesh K Harijan, Tiila-riikka Kiema, Rikkert K Wierenga, M R N MurthyAbstract:Thiolases catalyze the degradation and synthesis of 3-ketoacyl-CoA molecules. Here, the crystal structures of a T1-like thiolase (MSM-13 thiolase) from Mycobacterium smegmatis in apo and liganded forms are described. Systematic comparisons of six crystallographically independent unliganded MSM-13 thiolase tetramers (dimers of tight dimers) from three different crystal forms revealed that the two tight dimers are connected to a rigid tetramerization domain via flexible hinge regions, generating an asymmetric tetramer. In the liganded structure, CoA is bound to those subunits that are rotated towards the tip of the tetramerization loop of the opposing dimer, suggesting that this loop is important for substrate binding. The hinge regions responsible for this rotation occur near Val123 and Arg149. The L alpha 1-covering loop-L alpha 2 region, together with the N beta 2-N alpha 2 loop of the adjacent subunit, defines a specificity pocket that is larger and more polar than those of other tetrameric thiolases, suggesting that MSM-13 thiolase has a distinct substrate specificity. Consistent with this finding, only residual activity was detected with acetoacetyl-CoA as the substrate in the degradative direction. No activity was observed with acetyl-CoA in the synthetic direction. Structural comparisons with other well characterized thiolases suggest that MSM-13 thiolase is probably a degradative thiolase that is specific for 3-ketoacyl-CoA molecules with polar, bulky acyl chains.
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Structural characterization of a mitochondrial 3-ketoacyl-CoA (T1)-like thiolase from Mycobacterium smegmatis.
Acta crystallographica. Section D Biological crystallography, 2015Co-Authors: Neelanjana Janardan, Rajesh K Harijan, Tiila-riikka Kiema, Rikkert K Wierenga, M R N MurthyAbstract:Thiolases catalyze the degradation and synthesis of 3-ketoacyl-CoA molecules. Here, the crystal structures of a T1-like thiolase (MSM-13 thiolase) from Mycobacterium smegmatis in apo and liganded forms are described. Systematic comparisons of six crystallographically independent unliganded MSM-13 thiolase tetramers (dimers of tight dimers) from three different crystal forms revealed that the two tight dimers are connected to a rigid tetramerization domain via flexible hinge regions, generating an asymmetric tetramer. In the liganded structure, CoA is bound to those subunits that are rotated towards the tip of the tetramerization loop of the opposing dimer, suggesting that this loop is important for substrate binding. The hinge regions responsible for this rotation occur near Val123 and Arg149. The Lα1-covering loop-Lα2 region, together with the Nβ2-Nα2 loop of the adjacent subunit, defines a specificity pocket that is larger and more polar than those of other tetrameric thiolases, suggesting that MSM-13 thiolase has a distinct substrate specificity. Consistent with this finding, only residual activity was detected with acetoacetyl-CoA as the substrate in the degradative direction. No activity was observed with acetyl-CoA in the synthetic direction. Structural comparisons with other well characterized thiolases suggest that MSM-13 thiolase is probably a degradative thiolase that is specific for 3-ketoacyl-CoA molecules with polar, bulky acyl chains.
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crystal structure of a monomeric thiolase like protein type 1 tlp1 from mycobacterium smegmatis
PLOS ONE, 2012Co-Authors: Neelanjana Janardan, Rajesh K Harijan, Rikkert K Wierenga, M R N MurthyAbstract:An analysis of the Mycobacterium smegmatis genome suggests that it codes for several thiolases and thiolase-like proteins. Thiolases are an important family of enzymes that are involved in fatty acid metabolism. They occur as either dimers or tetramers. Thiolases catalyze the Claisen condensation of two acetyl-Coenzyme A molecules in the synthetic direction and the thiolytic cleavage of 3-ketoacyl-Coenzyme A molecules in the degradative direction. Some of the M. smegmatis genes have been annotated as thiolases of the poorly characterized SCP2-thiolase subfamily. The mammalian SCP2-thiolase consists of an N-terminal thiolase domain followed by an additional C-terminal domain called sterol carrier protein-2 or SCP2. The M. smegmatis protein selected in the present study, referred to here as the thiolase-like protein type 1 (MsTLP1), has been biochemically and structurally characterized. Unlike classical thiolases, MsTLP1 is a monomer in solution. Its structure has been determined at 2.7 angstrom resolution by the single wavelength anomalous dispersion method. The structure of the protomer confirms that the N-terminal domain has the thiolase fold. An extra C-terminal domain is indeed observed. Interestingly, it consists of six beta-strands forming an anti-parallel beta-barrel which is completely different from the expected SCP2-fold. Detailed sequence and structural comparisons with thiolases show that the residues known to be essential for catalysis are not conserved in MsTLP1. Consistent with this observation, activity measurements show that MsTLP1 does not catalyze the thiolase reaction. This is the first structural report of a monomeric thiolase-like protein from any organism. These studies show that MsTLP1 belongs to a new group of thiolase related proteins of unknown function.
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the sulfur atoms of the substrate coa and the catalytic cysteine are required for a productive mode of substrate binding in bacterial biosynthetic thiolase a thioester dependent enzyme
FEBS Journal, 2008Co-Authors: Gitte Merilainen, Werner Schmitz, Rikkert K Wierenga, Petri KursulaAbstract:Thioesters are more reactive than oxoesters, and thioester chemistry is important for the reaction mechanisms of many enzymes, including the members of the thiolase superfamily, which play roles in both degradative and biosynthetic pathways. In the reaction mechanism of the biosynthetic thiolase, the thioester moieties of acetyl-CoA and the acetylated catalytic cysteine react with each other, forming the product acetoacetyl-CoA. Although a number of studies have been carried out to elucidate the thiolase reaction mechanism at the atomic level, relatively little is known about the factors determining the affinity of thiolases towards their substrates. We have carried out crystallographic studies on the biosynthetic thiolase from Zoogloea ramigera complexed with CoA and three of its synthetic analogues to compare the binding modes of these related compounds. The results show that both the CoA terminal SH group and the side chain SH group of the catalytic Cys89 are crucial for the correct positioning of substrate in the thiolase catalytic pocket. Furthermore, calorimetric assays indicate that the mutation of Cys89 into an alanine significantly decreases the affinity of thiolase towards CoA. Thus, although the sulfur atom of the thioester moiety is important for the reaction mechanism of thioester-dependent enzymes, its specific properties can also affect the affinity and competent mode of binding of the thioester substrates to these enzymes.
Nallani Satyanarayana - One of the best experts on this subject based on the ideXlab platform.
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Densities and Speeds of Sound for Binary Liquid Mixtures of Thiolane-1,1-dioxide with Butanone, Pentan-2-one, Pentan-3-one, and 4-Methyl-pentan-2-one at T ) (303.15 or 308.15 or 313.15) K
Journal of Chemical & Engineering Data, 2009Co-Authors: Patwari Murali Krishna, Bachu Ranjith Kumar, Boodida Sathyanarayana, Kanthala Sampath Kumar, Nallani SatyanarayanaAbstract:Experimental data on density (ρ) and speed of sound (u) at (303.15, 308.15, and 308.15) K are presented for the binary mixtures of (Thiolane-1,1-dioxide + butanone), (Thiolane-1,1-dioxide + pentan-2-one), (Thiolane-1,1-dioxide + pentan-3-one), and (Thiolane-1,1-dioxide + 4-methyl-pentan-2-one). From this data, excess molar volume and deviation in isentropic compressibility have been calculated. The Redlich−Kister polynomial equation was fitted to the experimental data.
M R N Murthy - One of the best experts on this subject based on the ideXlab platform.
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structural characterization of a mitochondrial 3 ketoacyl coa t1 like thiolase from mycobacterium smegmatis
Acta Crystallographica Section D-biological Crystallography, 2015Co-Authors: Neelanjana Janardan, Rajesh K Harijan, Tiila-riikka Kiema, Rikkert K Wierenga, M R N MurthyAbstract:Thiolases catalyze the degradation and synthesis of 3-ketoacyl-CoA molecules. Here, the crystal structures of a T1-like thiolase (MSM-13 thiolase) from Mycobacterium smegmatis in apo and liganded forms are described. Systematic comparisons of six crystallographically independent unliganded MSM-13 thiolase tetramers (dimers of tight dimers) from three different crystal forms revealed that the two tight dimers are connected to a rigid tetramerization domain via flexible hinge regions, generating an asymmetric tetramer. In the liganded structure, CoA is bound to those subunits that are rotated towards the tip of the tetramerization loop of the opposing dimer, suggesting that this loop is important for substrate binding. The hinge regions responsible for this rotation occur near Val123 and Arg149. The L alpha 1-covering loop-L alpha 2 region, together with the N beta 2-N alpha 2 loop of the adjacent subunit, defines a specificity pocket that is larger and more polar than those of other tetrameric thiolases, suggesting that MSM-13 thiolase has a distinct substrate specificity. Consistent with this finding, only residual activity was detected with acetoacetyl-CoA as the substrate in the degradative direction. No activity was observed with acetyl-CoA in the synthetic direction. Structural comparisons with other well characterized thiolases suggest that MSM-13 thiolase is probably a degradative thiolase that is specific for 3-ketoacyl-CoA molecules with polar, bulky acyl chains.
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Structural characterization of a mitochondrial 3-ketoacyl-CoA (T1)-like thiolase from Mycobacterium smegmatis.
Acta crystallographica. Section D Biological crystallography, 2015Co-Authors: Neelanjana Janardan, Rajesh K Harijan, Tiila-riikka Kiema, Rikkert K Wierenga, M R N MurthyAbstract:Thiolases catalyze the degradation and synthesis of 3-ketoacyl-CoA molecules. Here, the crystal structures of a T1-like thiolase (MSM-13 thiolase) from Mycobacterium smegmatis in apo and liganded forms are described. Systematic comparisons of six crystallographically independent unliganded MSM-13 thiolase tetramers (dimers of tight dimers) from three different crystal forms revealed that the two tight dimers are connected to a rigid tetramerization domain via flexible hinge regions, generating an asymmetric tetramer. In the liganded structure, CoA is bound to those subunits that are rotated towards the tip of the tetramerization loop of the opposing dimer, suggesting that this loop is important for substrate binding. The hinge regions responsible for this rotation occur near Val123 and Arg149. The Lα1-covering loop-Lα2 region, together with the Nβ2-Nα2 loop of the adjacent subunit, defines a specificity pocket that is larger and more polar than those of other tetrameric thiolases, suggesting that MSM-13 thiolase has a distinct substrate specificity. Consistent with this finding, only residual activity was detected with acetoacetyl-CoA as the substrate in the degradative direction. No activity was observed with acetyl-CoA in the synthetic direction. Structural comparisons with other well characterized thiolases suggest that MSM-13 thiolase is probably a degradative thiolase that is specific for 3-ketoacyl-CoA molecules with polar, bulky acyl chains.
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crystal structure of a monomeric thiolase like protein type 1 tlp1 from mycobacterium smegmatis
PLOS ONE, 2012Co-Authors: Neelanjana Janardan, Rajesh K Harijan, Rikkert K Wierenga, M R N MurthyAbstract:An analysis of the Mycobacterium smegmatis genome suggests that it codes for several thiolases and thiolase-like proteins. Thiolases are an important family of enzymes that are involved in fatty acid metabolism. They occur as either dimers or tetramers. Thiolases catalyze the Claisen condensation of two acetyl-Coenzyme A molecules in the synthetic direction and the thiolytic cleavage of 3-ketoacyl-Coenzyme A molecules in the degradative direction. Some of the M. smegmatis genes have been annotated as thiolases of the poorly characterized SCP2-thiolase subfamily. The mammalian SCP2-thiolase consists of an N-terminal thiolase domain followed by an additional C-terminal domain called sterol carrier protein-2 or SCP2. The M. smegmatis protein selected in the present study, referred to here as the thiolase-like protein type 1 (MsTLP1), has been biochemically and structurally characterized. Unlike classical thiolases, MsTLP1 is a monomer in solution. Its structure has been determined at 2.7 angstrom resolution by the single wavelength anomalous dispersion method. The structure of the protomer confirms that the N-terminal domain has the thiolase fold. An extra C-terminal domain is indeed observed. Interestingly, it consists of six beta-strands forming an anti-parallel beta-barrel which is completely different from the expected SCP2-fold. Detailed sequence and structural comparisons with thiolases show that the residues known to be essential for catalysis are not conserved in MsTLP1. Consistent with this observation, activity measurements show that MsTLP1 does not catalyze the thiolase reaction. This is the first structural report of a monomeric thiolase-like protein from any organism. These studies show that MsTLP1 belongs to a new group of thiolase related proteins of unknown function.
N. T. Kulishkin - One of the best experts on this subject based on the ideXlab platform.
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Hydrogenation of 3-thiolene-1,1-dioxide on Pd catalysts
Reaction Kinetics and Catalysis Letters, 1997Co-Authors: A. V. Mashkina, N. T. KulishkinAbstract:Liquid-phase hydrogenation of 3-thiolene-1,1-dioxide to Thiolane-1,1-dioxide on Pd catalysts has been studied. According to the kinetic and adsorption data, at 20°C and P_H _2=0.1–1.0 MPa the reaction proceeds via the interaction of adsorbed 3-thiolene-1,1-dioxide with dissolved H_2. At P_H _2=2–7 MPa, the reaction between the adsorbed H_2 and dissolved 3-thiolene-1,1-dioxide is the limiting step of the process.
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Activity and stability of rhodium catalysts in liquid-phase hydrogenation of 3-thiolene-1, 1-dioxide
Reaction Kinetics and Catalysis Letters, 1991Co-Authors: N. T. Kulishkin, A. V. MashkinaAbstract:Активность и устойчивость родиевых катализоторов изменяется симбатно изменению дисперсности металла. Обработка образцов после восстановления воздухом приводит к значительному (3–5 раз) повышению нх активности в реакции гидрирования 3-тиолен-1, 1-диоксида в тиолан-1, 1-диоксид. Activity and stability of rhodium catalysts is found to vary in parallel with metal dispersity. Treatment of reduced samples by air leads to a considerable (3–5 fold) increase of their activity in hydrogenation of 3-thiolene-1,1-dioxide to Thiolane-1,1-dioxide.
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Influence of preparation conditions on activity and stability of catalysts for 3-thiolene-1, 1-dioxide hydrogenation
Reaction Kinetics and Catalysis Letters, 1991Co-Authors: N. T. Kulishkin, A. V. MashkinaAbstract:Дисперсность нанесенного на γ-Al_2O_3 палладия, активность и устойчивость катализаторов в реакции гидрирования 3-тиолен-1,1-диоксида в тиолан-1,1-диоксид существенно зависят от состава пропиточного раствора и дополнительной перед восстановлением химической обработки. Это влияние определяется изменением подвижности иона Pd^2+ по поверхности носителя. Dispersity of γ-Al_2O_3-supported palladium and activity and selectivity of these catalysts in hydrogenation of 3-thiolene-1,1-dioxide to Thiolane-1,1-dioxide have been found to be dependent on the composition of impregnating solutions and the additional chemical treatment prior to reduction. This effect is due to the changes in Pd^2+ mobility over the support surface.
