Comparative inhibition profiles of human brain and mouse liver L-hexonate dehydrogenase

The inhibition profiles of mouse liver and human brain hexonate dehydrogenase were compared. In general, the pattern for fluoride, lithium, phenobarbital, hydroxylamine and iodoacetate inhibition is similar. Contrary to previous findings, the mouse liver enzyme is potently inhibited by cupric and mercuric ions in sub-millimolar concentrations. The human brain enzyme is also inhibited by these cations. Inhibition of both enzymes by thiol-blocking agents (p-chloromercuribenzoate, iodoacetate) and enzyme protection by the first substrate NADPH but not by the second substrate, glucuronate suggests that both enzymes contain thiol groups essential for catalytic activity.