Kinetic analysis of the effects of monovalent cations and divalent metals on the activity of Mycobacterium tuberculosis α-isopropylmalate synthase

Luiz Pedro S de Carvalho, John S. Blanchard

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Mycobacterium tuberculosis α-isopropylmalate synthase (MtIPMS) is a member of the family of enzymes that catalyze a Claisen-type condensation. In this work we characterized the monovalent and divalent specificity of MtIPMS using steady-state kinetics. The monovalent cation dependence of the kinetic parameters of substrates and divalent metals indicates that K+ is the likely physiological activator. K+ acts most likely as an allosteric activator, and exerts part of its effect through the catalytic divalent metal. The divalent metal specificity of MtIPMS is broad, and Mg2+ and Mn2+ are the metals that cause the highest activation. Interestingly, Zn2+, first assigned as the catalytic metal, inhibits the enzyme with submicromolar affinity. The features of monovalent cation and divalent metal activation, as well as the inhibition by Zn2+ and Cd2+, are discussed in light of the kinetic and structural information available for MtIPMS and other relevant enzymes.

Original languageEnglish (US)
Pages (from-to)141-148
Number of pages8
JournalArchives of Biochemistry and Biophysics
Volume451
Issue number2
DOIs
StatePublished - Jul 15 2006

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Monovalent Cations
Mycobacterium tuberculosis
Metals
Kinetics
Enzymes
Chemical activation
Kinetic parameters
Condensation
Substrates

Keywords

  • α-Isopropylmalate synthase
  • Activation
  • Divalent metal
  • l leucine
  • Metal ion activation
  • Monovalent cation
  • Steady-state kinetics
  • Tuberculosis

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

Cite this

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title = "Kinetic analysis of the effects of monovalent cations and divalent metals on the activity of Mycobacterium tuberculosis α-isopropylmalate synthase",
abstract = "Mycobacterium tuberculosis α-isopropylmalate synthase (MtIPMS) is a member of the family of enzymes that catalyze a Claisen-type condensation. In this work we characterized the monovalent and divalent specificity of MtIPMS using steady-state kinetics. The monovalent cation dependence of the kinetic parameters of substrates and divalent metals indicates that K+ is the likely physiological activator. K+ acts most likely as an allosteric activator, and exerts part of its effect through the catalytic divalent metal. The divalent metal specificity of MtIPMS is broad, and Mg2+ and Mn2+ are the metals that cause the highest activation. Interestingly, Zn2+, first assigned as the catalytic metal, inhibits the enzyme with submicromolar affinity. The features of monovalent cation and divalent metal activation, as well as the inhibition by Zn2+ and Cd2+, are discussed in light of the kinetic and structural information available for MtIPMS and other relevant enzymes.",
keywords = "α-Isopropylmalate synthase, Activation, Divalent metal, l leucine, Metal ion activation, Monovalent cation, Steady-state kinetics, Tuberculosis",
author = "{de Carvalho}, {Luiz Pedro S} and Blanchard, {John S.}",
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AU - de Carvalho, Luiz Pedro S

AU - Blanchard, John S.

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Y1 - 2006/7/15

N2 - Mycobacterium tuberculosis α-isopropylmalate synthase (MtIPMS) is a member of the family of enzymes that catalyze a Claisen-type condensation. In this work we characterized the monovalent and divalent specificity of MtIPMS using steady-state kinetics. The monovalent cation dependence of the kinetic parameters of substrates and divalent metals indicates that K+ is the likely physiological activator. K+ acts most likely as an allosteric activator, and exerts part of its effect through the catalytic divalent metal. The divalent metal specificity of MtIPMS is broad, and Mg2+ and Mn2+ are the metals that cause the highest activation. Interestingly, Zn2+, first assigned as the catalytic metal, inhibits the enzyme with submicromolar affinity. The features of monovalent cation and divalent metal activation, as well as the inhibition by Zn2+ and Cd2+, are discussed in light of the kinetic and structural information available for MtIPMS and other relevant enzymes.

AB - Mycobacterium tuberculosis α-isopropylmalate synthase (MtIPMS) is a member of the family of enzymes that catalyze a Claisen-type condensation. In this work we characterized the monovalent and divalent specificity of MtIPMS using steady-state kinetics. The monovalent cation dependence of the kinetic parameters of substrates and divalent metals indicates that K+ is the likely physiological activator. K+ acts most likely as an allosteric activator, and exerts part of its effect through the catalytic divalent metal. The divalent metal specificity of MtIPMS is broad, and Mg2+ and Mn2+ are the metals that cause the highest activation. Interestingly, Zn2+, first assigned as the catalytic metal, inhibits the enzyme with submicromolar affinity. The features of monovalent cation and divalent metal activation, as well as the inhibition by Zn2+ and Cd2+, are discussed in light of the kinetic and structural information available for MtIPMS and other relevant enzymes.

KW - α-Isopropylmalate synthase

KW - Activation

KW - Divalent metal

KW - l leucine

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KW - Steady-state kinetics

KW - Tuberculosis

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