The rate of MgADP binding to and dissociation from acto-S1

J. Borejdo, T. Ando, T. P. Burghardt

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The rate of binding and dissociation of MgADP from its ternary complex with actin and S1 was measured by following the extent to which fixed concentrations of MgADP slow down MgATP-induced dissociation of acto-S1. The solution of the equations describing this process shows that at any MgADP concentration the apparent rate of acto-S1 dissociation should be proportional to a square root of the equilibrium constant for MgADP dissociation and to MgATP concentration. By measuring the apparent rate of acto-S1 dissociation as a function of MgATP concentration, the rate of MgADP binding and dissociation were determined as 5 · 106 M-1 · s-1 and 1400 s-1, respectively. These rates were unchanged by modification of SH1 thiol of S1 by a variety of fluorescence and spin-labels, but dissociation rate was drastically reduced when SH1 was labelled with 5-iodoacetamidofluorescein.

Original languageEnglish
Pages (from-to)172-176
Number of pages5
JournalBiochimica et Biophysica Acta (BBA)/Protein Structure and Molecular
Volume828
Issue number2
DOIs
StatePublished - 5 Apr 1985

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pioglitazone
Adenosine Diphosphate
Adenosine Triphosphate
Spin Labels
Sulfhydryl Compounds
Equilibrium constants
Fluorescence

Keywords

  • (Rabbit skeletal muscle)
  • Actin-myosin interaction
  • Dissociation rate constant
  • Fluorescence probe
  • MgADP binding
  • Myosin subfragment 1

Cite this

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The rate of MgADP binding to and dissociation from acto-S1. / Borejdo, J.; Ando, T.; Burghardt, T. P.

In: Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular, Vol. 828, No. 2, 05.04.1985, p. 172-176.

Research output: Contribution to journalArticle

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AU - Ando, T.

AU - Burghardt, T. P.

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N2 - The rate of binding and dissociation of MgADP from its ternary complex with actin and S1 was measured by following the extent to which fixed concentrations of MgADP slow down MgATP-induced dissociation of acto-S1. The solution of the equations describing this process shows that at any MgADP concentration the apparent rate of acto-S1 dissociation should be proportional to a square root of the equilibrium constant for MgADP dissociation and to MgATP concentration. By measuring the apparent rate of acto-S1 dissociation as a function of MgATP concentration, the rate of MgADP binding and dissociation were determined as 5 · 106 M-1 · s-1 and 1400 s-1, respectively. These rates were unchanged by modification of SH1 thiol of S1 by a variety of fluorescence and spin-labels, but dissociation rate was drastically reduced when SH1 was labelled with 5-iodoacetamidofluorescein.

AB - The rate of binding and dissociation of MgADP from its ternary complex with actin and S1 was measured by following the extent to which fixed concentrations of MgADP slow down MgATP-induced dissociation of acto-S1. The solution of the equations describing this process shows that at any MgADP concentration the apparent rate of acto-S1 dissociation should be proportional to a square root of the equilibrium constant for MgADP dissociation and to MgATP concentration. By measuring the apparent rate of acto-S1 dissociation as a function of MgATP concentration, the rate of MgADP binding and dissociation were determined as 5 · 106 M-1 · s-1 and 1400 s-1, respectively. These rates were unchanged by modification of SH1 thiol of S1 by a variety of fluorescence and spin-labels, but dissociation rate was drastically reduced when SH1 was labelled with 5-iodoacetamidofluorescein.

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