Abstract
The distribution of glutathione S-transferase (GST) (EC 2.5.1.18) in yeasts was investigated. High enzyme activity was found in some strains of Issatchenkia and Candida. Of 168 strains tested, Iss. orientalis showed the highest activity. The enzyme activity exists constitutively in the yeast cells but it increased with the addition of an enzyme substrate, o-dinitrobenzene, to the culture medium. Moreover, the addition of L-cysteine and glycine to the medium also increased the enzyme activity. This enzyme was so unstable that it lost almost all its activity on ammonium sulfate precipitation and 93% of its activity was lost when it was stored at 4°C for two weeks in a soluble state. We found that it was stabilized considerably in a solution containing 20% glycerol, 1 mM EDTA, 2 mM DTT and 10 mM sodium sulfite.
