Activation of serine sulphydrase from baker's yeast (Saccharomyces cerevisiae) by vanadate

Vanadate stimulates the liberation of H2S from cysteine in intact cells of baker's yeast (Saccharomyces cerevisiae) with a maximal increase of 60% at 10 microM NH4VO3. Protein separation from crude yeast extract yielded two active protein fractions which were found to catalyze the degradation of cysteine to H2S, pyruvate and ammonia or H2S and serine, respectively, thus characterizing them as cysteine desulphydrase and serine sulphydrase. Only the latter enzyme was found to be activated by vanadate, showing optimal enhancement of about 100% at 10 microM NH4VO3.