Purificaton and characterization of S-formylglutathione hydrolase from a methanol-utilizing yeast, Kloeckera sp. No. 2201.

S-Fromylglutathione hydrolase (EC 3.1.2.12), a glutathione thiol esterase, was purified from a methanol-utilizing yeast, Kloeckera sp. No. 2201, to homogeneity as judged by polyacrylamide gel electrophoresis. The molecular weight of the native enzyme was determined to be 58 000 by gel filtration. The enzyme appeared to be composed of two identical subunits (Mr = 31 000). The apparent Km for S-formylglutathione was 0.077 mM. The optimum temperature was 50 degrees C and the optimum pH was 6.4-6.6. The enzyme was inhibited by several types of sulfhydryl reagents. The purified enzyme preparation contained no activity of formaldehyde dehydrogenase or of formate dehydrogenase. It is thought that three enzymes, formaldehyde dehydrogenase, S-formylglutathione hydrolase and formate dehydrogenase, participate in the oxidation of formaldehyde to CO2 in Kloeckera sp. No. 2201.