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J Biol Chem. 1990 Jan 5;265(1):171-6.

Kinetics of ATP and inorganic phosphate release during hydrolysis of ATP by rabbit skeletal actomyosin subfragment 1. Oxygen exchange between water and ATP or phosphate.

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1
Division of Physical Biochemistry, National Institute for Medical Research, London, United Kingdom.

Abstract

We have used the technique of phosphate: water oxygen exchange to measure the rate of ATP and Pi release and Pi binding to myosin subfragment 1 and actomyosin subfragment 1 from rabbit skeletal muscle. The oxygen exchange distributions for ATP and Pi release fit a simple kinetic model with a single set of rate constants for each step. For actomyosin subfragment 1 (20 degrees C, pH 7.0, I = 50 mM), the rate constant governing ATP release is approximately 8 s-1, Pi release is at approximately 60 s-1 and Pi rebinds to an ADP state at greater than 120 M-1 s-1. These rate constants are similar to those that may occur for undistorted cross-bridges within glycerinated rabbit psoas fibers (Bowater, R., Webb, M. R., and Ferenczi, M. A. (1989) J. Biol. Chem. 264, 7193-7201.

PMID:
2136736
[Indexed for MEDLINE]
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