Some Kinetic Singularities of Mg2+-Dependent Mn-ATPase in Rat Brain Synaptic Membranes |
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Authors: | Nino Kvitsinadze Gvantsa Chkadua Lia Shioshvili Zurab Kometiani |
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Institution: | Department of Membranology, Life Science Research Center, 14, Gotua Str, 0160, Tbilisi, Georgia. Kvitsinadze-nino@rambler.ru |
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Abstract: | Mn(2+) stimulated change of Mg-ATPase activity has been found in the synaptic fraction of rat brain that was named Mn-ATPase. Investigation of the molecular mechanism has shown that Mn-ATPase is a multi-sited enzyme system whose minimum functional unit is a dimer. Its substrate is the MgATP complex. The number of sites for Mn(2+) as for essential activators and that of full-effect inhibitors are equal, n?=?m?=?1. Studying regulation of the Mn-ATPase system by Mg(2+) has shown that Mg(2+) represents a double-sided effect modifier, namely, it activates the enzyme system at low concentration but inhibits at high concentration. Supposedly, binding-release of MgATP and Mg(2+) from the enzyme would be performed by a randomized mechanism. When analyzing experiments by using the kinetic method of complex curves, a "minimal model" for Mn-ATPase has been created. |
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