The interaction o f C u 2+ with enzymatic activity o f rabbit kidney N a + /K +-ATPase was studied in media w ith buf fered, defined free C u 2+ levels. The IC 50-values are 0.1 ¿imol/1 for N a*/K +-ATPase and 1 ¿¿mo 1/1 for K +-pNPPase. Dithiothreitol (DTT) reverses the inhibitory effect o f C u2+ in vitro. C u 2+ exerts non-competitive effects on the enzyme with respect to N a +, K +, ATP or pNPP, but has a mixed-type inhibitory effect with respect to M g 2+. It is concluded that the appreciation o f the inhibitory effect o f C u 2+ on this enzyme requires carefully composed assay media that in clude a buffer for C u 24', and that the IC 50-values calculated according to this model indicate that C u 2+ may be more toxic than previously anticipated.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.