Ryuichiro Kurane

Some General Properties of the Purified Thiol: Disulfide Oxidoreductase from Candida claussenii

This paper presents some data on general properties of the purified thiol: disulfide oxi-doreductases (D–l–1) and (D–2) from Candida claussenii. The optimum pH for both purified enzymes was pH 8.0 and the optimum temperatures for D–l–1 and D–2 were 40°C and 50°C, respectively. Both purified enzymes were stable below 30°C and in a pH range from 5.0 to 8.0 at 5°C. The enzyme activity was inhibited with several metals. Hg2+ and transition metals were the most toxic. The substrate specificities of both enzymes were wide, not only for the low molecular weight compounds but also for high molecular weight compounds, such as albumin and insulin. Various sulfhydryl-groups could serve as hydrogen donor.Consequently, the reaction mode of these thiol: disulfide oxidoreductases was represented as follows: Both enzymes had similar biochemical properties, but the molecular weights of D–l–1 and D–2 differed: the former, 155,000~170,000 and the latter, 29,000~31,000.The enzyme activity was distributed in all subcellular f...