Kinetic studies of mercuric chloride on Na+ K+-ATPase in the kidney of fancy carp, Cyprinus carpio

Abstract

1. 1. The effect of mercuric chloride on the substrate and ionic activation kinetics of Na+ K+-ATPase activity in the kidney of fancy carp (Cyprinus carpio) was determined. 2. 2. Mercuric inhibition was shown to be a classical competitive nature with respect to substrate ATP activated Na+ K+-ATPase, in that the apparent Km values were increased without a significant change in the apparent Vmax values. 3. 3. Mercuric inhibition was a mixed noncompetitive nature with respect to Na+-activated Na+ K+-ATPase, where the apparent Km values were increased but the apparent Vmax values were decreased. 4. 4. Mercuric inhibition was a pure noncompetitive nature with respect to Mg2+ and K+-activated Na+ K+-ATPase, in that the apparent Vmax values were decreased but not the apparent Km values. 5. 5. Based on the above results, we proposed a possible kinetic model for elucidating the biochemical mechanism of inhibition of mercuric chloride on Na+ K+-ATPase in the kidney of fancy carp. © 1993.