THE METHYLATION OF ARSENATE BY A MARINE ALGA POLYPHYSA-PENICULUS IN THE PRESENCE OF L-METHIONINE-METHYL-D(3)

Polyphysa peniculus growing in artificial seawater methylates arsenate to produce a dimethylarsenic derivative, probably dimethylarsinate. When L-methionine-methyl-d3 is added to the culture the CD3 label is incorporated intact in the dimethylarsenic compound to a considerable extent, indicating that S-adenosylmethionine, or some related sulphonium compound, is involved in the biological methylation. Conclusive evidence of the CD3 incorporation was provided by using a specially developed hydride generation-gas chromatography-mass spectrometry methodology.