THE METABOLISM OF CYSTINE AND CYSTEINE BY PROTEUS VULGARIS AND PROTEUS MORGANII

Abstract

Resting cells of P. morganii and P. vulgaris dissimilate cystine to cysteine; the latter is then metabolized to pyruvate, H2S and ammonia. The system is inhibited bv carbonyl reagents and arsenite but not by [alpha],[alpha][image] -dipyridyl, 8-hydroxylamine, NaN3 or amino acids. P. morganii liberates H2S from cysteine and homocysteine while P. vulgaris attacks only the former. Toluene treatment of P. morganii yields non-viable cells active against cysteine, homo-cysteine and serine but unable to attack cystine or pyruvate. Maximal desulfhydrase activities were observed in cells grown anaerobically in the presence of cystine or cysteine.