FIG. 3.

Challenger mechanism for the conversion of arsenate to trimethylarsine. (A) Arsenate; (B) arsenite; (C) methylarsonate; (D) methylarsonite; (E) dimethylarsinate; (F) dimethylarsinite; (G) trimethylarsine oxide; (H) trimethylarsine. The top line of structures shows the As(V) intermediates. The vertical arrows indicate the reduction reactions to the As(III) intermediates (bottom line), and the diagonal arrows indicate the methylation steps by SAM (see Fig. 2 for details of the reduction and methylation processes).