This is a rapid method with sufficient precision to give reliable results on large numbers of research and control samples of condensed phosphates and phosphate detergents. The modified solvents and use of the densitometer each contribute to the saving of considerable time over previously published methods. One operator can evaluate 20 samples per day with time during running, drying, etc., for other work.If it is desired to use an elution tech-nique for evaluation (1, 4~7), use of the modified solvents will decrease the time needed for separation and eliminate the necessity for a two-solvent, two-dimensional separation.

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Summary. Investigationl on the biosynthesis of S-methyl-L-cysteine in radish leaves has shown that it is formed by the methylation of cysteine. This conclusioii is based on: A) the relatively high recovery of radioactivity in methylcysteine sulfoxide after the administration of cysteine or methyl-labeled methionine to radish leaves; B) the nearly complete recovery of label from methyl-labeled methionine in the methyl group of methylcysteine sulfoxide; and C) the similarity in the ratio of tritium to 14C in methylcysteine sulfoxide and in its methyl group to this ratio in the methyl group of methionine given to radish leaves. Direct evidence for the synthesis of methylcysteine in radishes was obtained for the first time.Conclusive evidence against the formation of methylcysteine from serine and a thiomethyl group from methionine as stuggested for garlic was the more efficient incorporation of the methyl group of methionine as compared to the sulfur atom into methylcysteine suilfoxide.S-Methyl-L-cysteine has been shown to be a nattural constituent of kidney bean seed (19) and . It is the putative precursor of methylcysteine sulfoxide (1) in crucifers. Wolff, Black and Downey (22) showed that methylmercaptan and serine were combined in the presence of yeast enzymes to form S-methylcysteine (equation I). CH3SH + CH2OHCHNH.,COOH -CH,SCH2CHNHXCOOH + H2O (I).More recently, Sugii and coworkers (15) have observed a high recovery of radioactivity in methylcysteine sulfoxide after feeding sulfuir labeled methionine to a garlic plant. The interpretation of this finding was that methylmercaptan was formed from methionine in garlic as in the rat (4) and that the methylmercaptan was then combined with serine as in the yeast system to form methylcysteine.In this paper, evidence is presented which indicates that S-methylcysteine is formed in radishes by methylation of cysteine. Materials and MethodsMethyl labeled methionine and unlabeled S-adenosylmethionine were obtained from Cal Biochem2. Method of Administrationt of Labeled and Unlabeled MIaterials to Radish Leaves. In order to carry out the studies described in this paper, it was necessary to have a method of getting quantitative uptake of radioactive compounds in a relatively short time, while simultaneously stupplying unlabeled compoulnds and preventing the leaf from wilting. The latter 2 problems were solved by the tuse of a collar around the petiole (fig 1). The handling of leaves and administration of labeled and unlabeled compouinds were carried out by the following procedures.An intact radish plant was dtug uip and immersed in water. The leaves were excised with a razor blade under water, rinsed, and transferred to distilled water. An alternative method which was not as reliable but saves plants was also employed. In the latter case, the leaves were excised withott tunearthing the plant and the entire petiole immediately immersed in distilled water. Any leaves which remained turgid after 4 to 6 hours at room temperature were used.The petiole was cleanied of any small ...

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