The enzymic properties of a modified ox heart myosin adenosine triphosphatase on covalent binding to an insoluble cellulose matrix |
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Authors: | Phyllis Liu-Osheroff and Richard John Guillory |
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Institution: | Section of Biochemistry and Molecular Biology, Cornell University, Ithaca, N.Y. 14850, U.S.A. |
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Abstract: | The preparation of ox heart myosin and its partial digestion with cellulose-bound papain is described. A procedure is outlined by which heavy meromyosin subfragment 1 can be covalently bound to a cellulose ion-exchange matrix. Attachment of heavy meromyosin subfragment 1 to the insoluble matrix results in a change in the ion specificity towards ATP hydrolysis. Unlike the soluble enzyme the bound form is activated by both Ca(2+) and Mg(2+). Maximal activation by Ca(2+) occurred at a lower concentration for the bound enzyme. Mg(2+) activates at a concentration which causes near-maximal inhibition of the Ca(2+)-activated adenosine triphosphatase (ATPase) of the non-bound enzyme. The Mg(2+)-activated ATPase of the bound enzyme was in turn inhibited by the presence of Ca(2+). The activation by Mg(2+) resembles the characteristic enzymic action of the actin-subfragment 1 complex. |
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