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Article Abstract
We used the gill (Na, K)-ATPase as a molecular marker to provide a comprehensive kinetic analysis of the effects of Coin vitro on the modulation of K-phosphatase activity in the Blue crab Callinectes danae. Co can stimulate or inhibit K-phosphatase activity. With Mg, K-phosphatase activity is almost completely inhibited by Co. Co stimulates K-phosphatase activity similarly to Mg although with a ≈4.5-fold greater affinity. At saturating Mg concentrations, Mg displaces bound Co from the Mg-binding site in a concentration dependent manner, but Co cannot displace Mg from its binding site even at millimolar concentrations. Saturation by Co of the Mg binding site does not affect pNPP recognition by the enzyme. Substitution of Mg by Co slightly increases enzyme affinity for K and NH. Independently of Mg, inhibition by ouabain or sodium ions is unaffected by Co. Investigation of gill (Na, K)-ATPase K-phosphatase activity provides a reliable tool to examine the kinetic effects of Co with and without Na and ATP. Given that the toxic effects of Co at the molecular level are poorly understood, these findings advance our knowledge of the mechanism of action of Co on the crustacean gill (Na, K)-ATPase.
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| http://dx.doi.org/10.1016/j.cbpc.2023.109757 | DOI Listing |
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