Abstract
1. In an attempt to follow out the correlation between the -SH contents and enzymatic activities studies were make on the effect of three main -SH reagents upon succinoxidase and α-ketoglutaric oxidase of isolated rat liver mitochondria as well as the reactivation experiments with GSH.
2. Mercaptide-forming agents such as PCMB, HgC12 and CuSO4 diminished the -SH content in exact agreement with the inhibition of the enzyme activities of both types (Figs. 1, 4). The addition of GSH restored not solely the succinoxidase activity, but also proportionately the -SH content of the protein.
3. Oxidizing agents such as tetrathionate and chloropicrin caused a reversible inhibition of succinoxidase activity, -SH groups disappearing at equal rate with enzyme activity, while both were restored to the same extent by the effect of GSH.
4. Zn++, Cd++, iodoacetamide and ferricyanide showed poor inhibition of enzyme activity and low affinity toward -SH groups of the isolated mitochondria (Figs. 1 and 2, Table I). Chlorovinyl-methyl-ketone showed relatively high affinity.
