Uncoupling of actomyosin adenosinetriphosphatase by heparin and its fragments

Uncoupling of actomyosin adenosinetriphosphatase by heparin and its fragments

Author Tersariol, Ivarne Luis dos Santos Autor UNIFESP Google Scholar
Dietrich, Carl Peter Autor UNIFESP Google Scholar
Nader, Helena Bonciani Autor UNIFESP Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Abstract Heparin and its enzymatic fragments, prepared by degradation of heparin with heparinase from Flavo-bacterium heparinum, were capable of inhibiting the actomyosin-ATPase activity obtained from striated and smooth vascular muscles. Heparin did not inhibit the myosin-ATPase activity in absence of actin. the results show that heparin changes the step of ATP hydrolysis of the complex actomyosin-ATPase by uncoupling the conformational transition on the myosin-head induced by actin upon the nucleotide-binding site. This mechanism is cooperative and dependent on conformational states of actomyosin complex which in turn is regulated by ATP and calcium levels. It was observed that in the presence of ATP, actin does not compete with heparin for binding to myosin showing that heparin and actin have different binding sites on myosin. the binding of heparin and ATP is cooperative suggesting that the nucleotide binding leads to an exposition of a second heparin-binding site. However, in the absence of ATP, actin competes with heparin for a binding site on the myosin. These results strongly suggest that in the weakly binding state of actin to myosin, the binding of heparin is powerful and in the rigor state its binding is decreased.
Keywords heparin
myosin ATPase
heparin and hemorrhagic activity
inhibition of actomyosin
Language English
Date 1997-04-01
Published in European Journal of Biochemistry. New York: Springer Verlag, v. 245, n. 1, p. 40-46, 1997.
ISSN 0014-2956 (Sherpa/Romeo, impact factor)
Publisher Springer
Extent 40-46
Origin http://dx.doi.org/10.1111/j.1432-1033.1997.00040.x
Access rights Open access Open Access
Type Article
Web of Science ID WOS:A1997WT20400005
URI http://repositorio.unifesp.br/handle/11600/25708

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