| Abstract: | The effects of the SH-groups binding agent p-chloromercurybenzoate (rho CMB) and the SH-containing compounds dithiothreitol (DTT), beta-mercaptoethanol (ME) and reduced glutathione (GSH) on activation by Mg2+ and K+ of ATPase in plasma membrane preparations from corn sprout root cells were studied. Rho CMB inhibited the ATPase activity, the degree of inhibition being directly dependent on the increase of the inhibitor concentration (from 10(-6) up to 10(-4) M); the inhibition was eliminated by the SH-containing agents (25 mM). DTT and ME added to the homogenization medium and ME added to the reaction mixture produced different effects on the ATPase activity of the membranes depending on the nature of the cations added. In the absence of the additives the ATPase activity was somewhat decreased, showing a sharp rise in the presence of Mg2+; an addition of K+ to a Mg2+-containing medium further increased the enzyme activity. GSH had no effect on the ATPase activation by the cations. |
