Abstract
We studied the reactivity of 2-ethylsulfonyl-7-methyl-5H-1, 3, 4-thiadiazolo[3, 2-a]pyrimidin-5-one (TPSO2-2) with some amino acids, SH, OH, and histidine enzymes. TPSO2-2 reacted with lcysteine in high yield (80-90%), but with glycine and L-serine in low yield (below 10%). To clarify the relative reactivity of TPSO2-2, its reaction with L-cysteine in the presence of ethanol and diethylamine was examined. TPSO2-2 reacted only with the SH group of L-cysteine, not with ethanol nor diethylamine. To elucidate the reactivity of TPSO2-2 toward enzymes, the inhibitory effects of TPSO2-2 on some enzymes containing cysteine, serine, or histidine in the active center were investigated. TPSO2-2 showed high inhibitory effects on SH enzymes, such as yeast alcohol dehydrogenase, glutamate dehydrogenase, and hexokinase, but no effect on trypsin, which has serine, or catalase, with histidine in the active center. TPSO2-2 appeared to be a specific inhibitor of SH enzymes.
