The Utilization of Carbon-1 Compounds by Plants: I. The Metabolism of Methanol-C14and Its Role in Amino Acid Biosynthesis

Methanol-C14was rapidly metabolized by carrot tissue slices, pea cotyledons, soybean cotyledons, castor bean endosperm, beet storage tissues, and mature beet leaves. With the exception of beet storage tissues, carbon dioxide was a chief product of methanol metabolism. In all tissues, methanol carbon was also incorporated in the organic acids, sugars, amino acids, and the insoluble residue. Serine, methionine, methionine sulfone, and methionine sulfoxide were important labelled components present in the amino acid fractions separated. Degradation of the serine-C14that was produced by carrot tissues metabolizing methanol-C14showed that the bulk of the label was present in the 3-position. The results are interpreted as indicating that methanol can act as a precursor of the carbon-1 units that are to be utilized in transmethylation reactions leading to serine and methionine biosynthesis. In addition, methanol can be oxidized to carbon dioxide by these tissues, and this reaction possibly involves dehydrogenase systems.