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Aminohydrolase

The Experts below are selected from a list of 66 Experts worldwide ranked by ideXlab platform

Edward P Whitehead – 1st expert on this subject based on the ideXlab platform

  • interaction of the high affinity inhibitor tetrahydro dump with the allosteric enzyme deoxycytidylate Aminohydrolase
    Archives of Biochemistry and Biophysics, 1994
    Co-Authors: Roberto Nucci, Carlo Vaccaro, Mosè Rossi, Ferdinando Febbraio, Gennaro Piccialli, L Denapoli, Edward P Whitehead

    Abstract:

    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.”

  • allosteric modifier and substrate binding of donkey deoxycytidylate Aminohydrolase ec 3 5 4 12
    Archives of Biochemistry and Biophysics, 1991
    Co-Authors: Roberto Nucci, Carlo A. Raia, Carlo Vaccaro, Mosè Rossi, Edward P Whitehead

    Abstract:

    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.

  • 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, 1991
    Co-Authors: Edward P Whitehead, Roberto Nucci, Carlo Vaccaro, Mosè Rossi

    Abstract:

    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.

Mosè Rossi – 2nd expert on this subject based on the ideXlab platform

  • interaction of the high affinity inhibitor tetrahydro dump with the allosteric enzyme deoxycytidylate Aminohydrolase
    Archives of Biochemistry and Biophysics, 1994
    Co-Authors: Roberto Nucci, Carlo Vaccaro, Mosè Rossi, Ferdinando Febbraio, Gennaro Piccialli, L Denapoli, Edward P Whitehead

    Abstract:

    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.”

  • allosteric modifier and substrate binding of donkey deoxycytidylate Aminohydrolase ec 3 5 4 12
    Archives of Biochemistry and Biophysics, 1991
    Co-Authors: Roberto Nucci, Carlo A. Raia, Carlo Vaccaro, Mosè Rossi, Edward P Whitehead

    Abstract:

    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.

  • 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, 1991
    Co-Authors: Edward P Whitehead, Roberto Nucci, Carlo Vaccaro, Mosè Rossi

    Abstract:

    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.

Roberto Nucci – 3rd expert on this subject based on the ideXlab platform

  • interaction of the high affinity inhibitor tetrahydro dump with the allosteric enzyme deoxycytidylate Aminohydrolase
    Archives of Biochemistry and Biophysics, 1994
    Co-Authors: Roberto Nucci, Carlo Vaccaro, Mosè Rossi, Ferdinando Febbraio, Gennaro Piccialli, L Denapoli, Edward P Whitehead

    Abstract:

    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.”

  • allosteric modifier and substrate binding of donkey deoxycytidylate Aminohydrolase ec 3 5 4 12
    Archives of Biochemistry and Biophysics, 1991
    Co-Authors: Roberto Nucci, Carlo A. Raia, Carlo Vaccaro, Mosè Rossi, Edward P Whitehead

    Abstract:

    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.

  • 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, 1991
    Co-Authors: Edward P Whitehead, Roberto Nucci, Carlo Vaccaro, Mosè Rossi

    Abstract:

    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.