The Experts below are selected from a list of 213 Experts worldwide ranked by ideXlab platform
Stephan König - One of the best experts on this subject based on the ideXlab platform.
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Significance of Individual Residues at the Regulatory Site of Yeast Pyruvate Decarboxylase for Allosteric Substrate Activation.
Biochemistry, 2017Co-Authors: Michael Spinka, Sebastian Seiferheld, Philipp Zimmermann, Elena Bergner, Anne-kathrin Blume, Angelika Schierhorn, Tom Reichenbach, Robert Pertermann, Christiane Ehrt, Stephan KönigAbstract:The catalytic activity of the Allosteric Enzyme pyruvate decarboxylase from yeast is strictly controlled by its own substrate pyruvate via covalent binding at a separate regulatory site. Kinetic st ...
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covalently bound substrate at the regulatory site of yeast pyruvate decarboxylases triggers Allosteric Enzyme activation
Journal of Biological Chemistry, 2009Co-Authors: Steffen Kutter, Michael Spinka, Georg Wille, Ralph Golbik, M S Weiss, Stephan KönigAbstract:The mechanism by which the Enzyme pyruvate decarboxylase from two yeast species is activated Allosterically has been elucidated. A total of seven three-dimensional structures of the Enzyme, of Enzyme variants, or of Enzyme complexes from two yeast species, three of them reported here for the first time, provide detailed atomic resolution snapshots along the activation coordinate. The prime event is the covalent binding of the substrate pyruvate to the side chain of cysteine 221, thus forming a thiohemiketal. This reaction causes the shift of a neighboring amino acid, which eventually leads to the rigidification of two otherwise flexible loops, one of which provides two histidine residues necessary to complete the enzymatically competent active site architecture. The structural data are complemented and supported by kinetic investigations and binding studies, providing a consistent picture of the structural changes occurring upon Enzyme activation.
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Covalently bound substrate at the regulatory site triggers Allosteric Enzyme activation
Nature Precedings, 2008Co-Authors: Steffen Kutter, Michael Spinka, Manfred Weiss, Georg Wille, Ralph Golbik, Stephan KönigAbstract:The mechanism by which the Enzyme pyruvate decarboxylase from yeast is activated Allosterically has been elucidated. A total of seven three-dimensional structures of the Enzyme, of Enzyme variants or of Enzyme complexes form two yeast species (three of them reported here for the first time) provide detailed atomic resolution snapshots along the activation coordinate. The prime event is the covalent binding of the substrate pyruvate to the side chain of cysteine 221, thus forming a thiohemiketal. This reaction causes the shift of a neighbouring amino acid, which eventually leads to the rigidification of two otherwise flexible loops, where one of the loops provides two histidine residues necessary to complete the enzymatically competent active site architecture. The structural data are complemented and supported by kinetic investigations and binding studies and provide a consistent picture of the structural changes, which occur upon Enzyme activation.
Michael Spinka - One of the best experts on this subject based on the ideXlab platform.
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Significance of Individual Residues at the Regulatory Site of Yeast Pyruvate Decarboxylase for Allosteric Substrate Activation.
Biochemistry, 2017Co-Authors: Michael Spinka, Sebastian Seiferheld, Philipp Zimmermann, Elena Bergner, Anne-kathrin Blume, Angelika Schierhorn, Tom Reichenbach, Robert Pertermann, Christiane Ehrt, Stephan KönigAbstract:The catalytic activity of the Allosteric Enzyme pyruvate decarboxylase from yeast is strictly controlled by its own substrate pyruvate via covalent binding at a separate regulatory site. Kinetic st ...
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covalently bound substrate at the regulatory site of yeast pyruvate decarboxylases triggers Allosteric Enzyme activation
Journal of Biological Chemistry, 2009Co-Authors: Steffen Kutter, Michael Spinka, Georg Wille, Ralph Golbik, M S Weiss, Stephan KönigAbstract:The mechanism by which the Enzyme pyruvate decarboxylase from two yeast species is activated Allosterically has been elucidated. A total of seven three-dimensional structures of the Enzyme, of Enzyme variants, or of Enzyme complexes from two yeast species, three of them reported here for the first time, provide detailed atomic resolution snapshots along the activation coordinate. The prime event is the covalent binding of the substrate pyruvate to the side chain of cysteine 221, thus forming a thiohemiketal. This reaction causes the shift of a neighboring amino acid, which eventually leads to the rigidification of two otherwise flexible loops, one of which provides two histidine residues necessary to complete the enzymatically competent active site architecture. The structural data are complemented and supported by kinetic investigations and binding studies, providing a consistent picture of the structural changes occurring upon Enzyme activation.
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Covalently bound substrate at the regulatory site triggers Allosteric Enzyme activation
Nature Precedings, 2008Co-Authors: Steffen Kutter, Michael Spinka, Manfred Weiss, Georg Wille, Ralph Golbik, Stephan KönigAbstract:The mechanism by which the Enzyme pyruvate decarboxylase from yeast is activated Allosterically has been elucidated. A total of seven three-dimensional structures of the Enzyme, of Enzyme variants or of Enzyme complexes form two yeast species (three of them reported here for the first time) provide detailed atomic resolution snapshots along the activation coordinate. The prime event is the covalent binding of the substrate pyruvate to the side chain of cysteine 221, thus forming a thiohemiketal. This reaction causes the shift of a neighbouring amino acid, which eventually leads to the rigidification of two otherwise flexible loops, where one of the loops provides two histidine residues necessary to complete the enzymatically competent active site architecture. The structural data are complemented and supported by kinetic investigations and binding studies and provide a consistent picture of the structural changes, which occur upon Enzyme activation.
Evan R. Kantrowitz - One of the best experts on this subject based on the ideXlab platform.
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Allostery and cooperativity in Escherichia coli Aspartate Transcarbamoylase
Archives of Biochemistry and Biophysics, 2011Co-Authors: Evan R. KantrowitzAbstract:The Allosteric Enzyme aspartate transcarbamoylase (ATCase) from Escherichia coli has been the subject of investigations for approximately 50 years. This Enzyme controls the rate of pyrimidine nucleotide biosynthesis by feedback inhibition, and helps to balance the pyrimidine and purine pools by competitive Allosteric activation by ATP. The catalytic and regulatory components of the dodecameric Enzyme can be separated and studied independently. Many of the properties of the Enzyme follow the Monod, Wyman Changeux model of Allosteric control thus E. coli ATCase has become the textbook example. This review will highlight kinetic, biophysical, and structural studies which have provided a molecular level understanding of how the Allosteric nature of this Enzyme regulates pyrimidine nucleotide biosynthesis.
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Trapping Specific Quaternary States of the Allosteric Enzyme Aspartate Transcarbamoylase in Silica Matrix Sol−Gels
Journal of the American Chemical Society, 2003Co-Authors: Jay M. West, Evan R. KantrowitzAbstract:The extreme T and R quaternary structures of the Allosteric Enzyme aspartate transcarbamoylase have been trapped by encapsulation in a silica sol−gel matrix. Detection of the specific quaternary structure present in the sol−gel was accomplished using a pyrene-labeled version of the Enzyme that exhibited monomer fluorescence in the T quaternary structure and excimer fluorescence in the R quaternary structure. Using thin films of the encapsulated Enzyme, kinetics of the T and R states could be determined without interconversion of the states. Using a monolith form of the encapsulated Enzyme, the transition from the T or the R structure was monitored. Within the sol−gel matrix, the rate of the transition was slowed approximately 105 over that observed in solution.
Edward P. Whitehead - One of the best experts on this subject based on the ideXlab platform.
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interaction of the high affinity inhibitor tetrahydro dump with the Allosteric Enzyme deoxycytidylate aminohydrolase
Archives of Biochemistry and Biophysics, 1994Co-Authors: Roberto Nucci, Carlo Vaccaro, L Denapoli, Ferdinando Febbraio, Gennaro Piccialli, Mose Rossi, Edward P. WhiteheadAbstract:Abstract Tetrahydro-dUMP, an analog of the putative transition state in aminohydrolysis of deoxycytidine monophosphate (dCMP) inhibits the Allosteric Enzyme deoxycytidylate aminohydrolase with high affinity. The inhibition is reversible, and its kinetics is consistent with the analog binding at the substrate site only to one and the same conformation that binds the substrate dCMP. Such kinetics is what would be expected for a transition state analog interacting in an Allosteric "K system."
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Allosteric modifier and substrate binding of donkey deoxycytidylate aminohydrolase ec 3 5 4 12
Archives of Biochemistry and Biophysics, 1991Co-Authors: Roberto Nucci, Carlo Vaccaro, Carlo A. Raia, Mose Rossi, Edward P. WhiteheadAbstract:Abstract The hexameric Allosteric Enzyme deoxycytidylate aminohydrolase from donkey spleen is shown by equilibrium dialysis to bind specifically the Allosteric inhibitor, dTTP, the activator dCTP, and the substrate analog dAMP each at six sites (the dTTP and dCTP sites may or may not be identical). These conclusions contrast with earlier ones that there were four sites for each effector; reasons for the discrepancy are discussed. With the knowledge of site numbers and the kinetic information from the accompanying paper it is concluded that the kinetic cooperativity of the Enzyme excludes a concerted conformational transition mechanism. Amino acid analysis gives a molecular weight of 18,842 Da per subunit, i.e., 113,052 for the hexamer. A new simplified purification of homogeneous Enzyme from donkey spleen probably useful for dCMP aminohydrolase from other sources is described.
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hill coefficient ratios give binding ratios of Allosteric Enzyme effectors inhibition activation and squatting in deoxycytidylate aminohydrolase ec 3 5 4 12
Archives of Biochemistry and Biophysics, 1991Co-Authors: Edward P. Whitehead, Carlo Vaccaro, Roberto Nucci, Mose RossiAbstract:Abstract The ratio of the steady-state kinetic Hill coefficients of two different effectors equals (under some rather weak general assumptions) the ratio in which the effectors displace each other from an Enzyme. This principle can make implications of experimental Allosteric Enzyme kinetic data immediately apparent. We can use it to find that one molecule of the Allosteric inhibitor of dCMP aminohydrolase, at moderately high effector concentrations, displaces one molecule of substrate, or one molecule of activator, whereas at very high concentrations, one molecule of inhibitor displaces two of substrate. Further use of the principle suggests that substrate, at high concentrations, binds to activator sites. However, ratios of substrate, activator, and inhibitor Hill coefficients are incompatible with a simple model of activation in which substrate and activator are bound to the same conformation.
Mose Rossi - One of the best experts on this subject based on the ideXlab platform.
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interaction of the high affinity inhibitor tetrahydro dump with the Allosteric Enzyme deoxycytidylate aminohydrolase
Archives of Biochemistry and Biophysics, 1994Co-Authors: Roberto Nucci, Carlo Vaccaro, L Denapoli, Ferdinando Febbraio, Gennaro Piccialli, Mose Rossi, Edward P. WhiteheadAbstract:Abstract Tetrahydro-dUMP, an analog of the putative transition state in aminohydrolysis of deoxycytidine monophosphate (dCMP) inhibits the Allosteric Enzyme deoxycytidylate aminohydrolase with high affinity. The inhibition is reversible, and its kinetics is consistent with the analog binding at the substrate site only to one and the same conformation that binds the substrate dCMP. Such kinetics is what would be expected for a transition state analog interacting in an Allosteric "K system."
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Allosteric modifier and substrate binding of donkey deoxycytidylate aminohydrolase ec 3 5 4 12
Archives of Biochemistry and Biophysics, 1991Co-Authors: Roberto Nucci, Carlo Vaccaro, Carlo A. Raia, Mose Rossi, Edward P. WhiteheadAbstract:Abstract The hexameric Allosteric Enzyme deoxycytidylate aminohydrolase from donkey spleen is shown by equilibrium dialysis to bind specifically the Allosteric inhibitor, dTTP, the activator dCTP, and the substrate analog dAMP each at six sites (the dTTP and dCTP sites may or may not be identical). These conclusions contrast with earlier ones that there were four sites for each effector; reasons for the discrepancy are discussed. With the knowledge of site numbers and the kinetic information from the accompanying paper it is concluded that the kinetic cooperativity of the Enzyme excludes a concerted conformational transition mechanism. Amino acid analysis gives a molecular weight of 18,842 Da per subunit, i.e., 113,052 for the hexamer. A new simplified purification of homogeneous Enzyme from donkey spleen probably useful for dCMP aminohydrolase from other sources is described.
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hill coefficient ratios give binding ratios of Allosteric Enzyme effectors inhibition activation and squatting in deoxycytidylate aminohydrolase ec 3 5 4 12
Archives of Biochemistry and Biophysics, 1991Co-Authors: Edward P. Whitehead, Carlo Vaccaro, Roberto Nucci, Mose RossiAbstract:Abstract The ratio of the steady-state kinetic Hill coefficients of two different effectors equals (under some rather weak general assumptions) the ratio in which the effectors displace each other from an Enzyme. This principle can make implications of experimental Allosteric Enzyme kinetic data immediately apparent. We can use it to find that one molecule of the Allosteric inhibitor of dCMP aminohydrolase, at moderately high effector concentrations, displaces one molecule of substrate, or one molecule of activator, whereas at very high concentrations, one molecule of inhibitor displaces two of substrate. Further use of the principle suggests that substrate, at high concentrations, binds to activator sites. However, ratios of substrate, activator, and inhibitor Hill coefficients are incompatible with a simple model of activation in which substrate and activator are bound to the same conformation.