The metabolism of methylarsine oxide and sulfide

Methylarsine oxide and sulfide are more toxic to Candida humicola than arsenite; the sulfide is rapidly metabolized to trimethylarsine (Me₃As) and methylarsine (MeAsH₂) and the oxide to dimethylarsinic acid Me₂AsO(OH)]. Cell-free extracts of C. humicola also convert the oxide to Me₂AsO(OH). The glutathione (RSH) derivative Me₂AsSR is metabolized by C. humicola to Me₃As and Me₂AsH, but some other Me₂AsSR′ compounds are unaffected. Studies involving the interaction of the arsenic(III) compounds with natural ecosystems and other micro-organisms such as Scopulariopsis brevicaulis, Straptococcus sanguis, Escherichia coli, and Veillonella alcalescens are described.