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

J. Borejdo; T. Ando; T. P. Burghardt

doi:10.1016/0167-4838(85)90054-8

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

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

Research output: Contribution to journal › Article › peer-review

4 Scopus citations

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 language	English
Pages (from-to)	172-176
Number of pages	5
Journal	Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular
Volume	828
Issue number	2
DOIs	https://doi.org/10.1016/0167-4838(85)90054-8
State	Published - 5 Apr 1985

Keywords

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

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10.1016/0167-4838(85)90054-8

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title = "The rate of MgADP binding to and dissociation from acto-S1",

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.",

keywords = "(Rabbit skeletal muscle), Actin-myosin interaction, Dissociation rate constant, Fluorescence probe, MgADP binding, Myosin subfragment 1",

author = "J. Borejdo and T. Ando and Burghardt, {T. P.}",

note = "Funding Information: We thank Ms. Carroll Flynn for excellent technical assistance and Professor M. Morales for support and Professor Roger Cooke for EPR measure- ments. This research was supported by grants HL-16683 from USPHS, PCM-7922174 from NSF and by a grant from Muscular Dystrophy Association. J.B. is an Established Investigator and T.P.B. is a postdoctoral fellow of the American Heart Association. Copyright: Copyright 2014 Elsevier B.V., All rights reserved.",

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doi = "10.1016/0167-4838(85)90054-8",

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AU - Ando, T.

AU - Burghardt, T. P.

N1 - Funding Information: We thank Ms. Carroll Flynn for excellent technical assistance and Professor M. Morales for support and Professor Roger Cooke for EPR measure- ments. This research was supported by grants HL-16683 from USPHS, PCM-7922174 from NSF and by a grant from Muscular Dystrophy Association. J.B. is an Established Investigator and T.P.B. is a postdoctoral fellow of the American Heart Association. Copyright: Copyright 2014 Elsevier B.V., All rights reserved.

PY - 1985/4/5

Y1 - 1985/4/5

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.

KW - (Rabbit skeletal muscle)

KW - Actin-myosin interaction

KW - Dissociation rate constant

KW - Fluorescence probe

KW - MgADP binding

KW - Myosin subfragment 1

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

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