Inhibition of rabbit muscle adenylate kinase by vitamin C.

Rabbit muscle adenylate kinase (EC 2.7.4.3) is completely inhibited, or nearly so, at 2 mM ascorbate, concentrations that are found in tissues. Kinetically, the inhibitions show classic non-competitive inhibition patterns against both substrates. Ascorbate inhibitions reverse completely in the presence of low concentrations of sulfhydryl compounds, such as mercaptoethanol, dithiothreitol, cysteine and glutathione. Dehydroascorbate inhibition is relatively poor and is also reversed by sulfhydryl compounds. Examination of the adenylate kinase inhibited by ascorbate with CD methodology showed no significant change in alpha-helix and beta-pleated sheet composition.