136757A0.Pdf
NOVEMBER 9, 1935 NATURE 757 quantitatively by the aspartase enzyme, and identified Using the ordinary technique, we have examined qualitatively in the form of the copper salt. Approxi specimens of purified l-fructose and l-arabinose, and mately the other half of the nitrogen ( 40-50 per cent) in neither event have we been able to detect the is precipitable by phosphotungstic acid. Since slightest reducing action on Tillmans's reagent. We cystine, arginine, histidine and aromatic amino acids have no explanation to offer of Jonnissian's results, are absent, it is probable that this fraction consists but we thought it might be of interest to publish of lycine. Further work is in progress to determine the above facts, in case that author's statements the nature of the compounds precipitated by phospho should lead other workers to under-value what has tungstic acid. come to be recognised as an extremely useful reagent. In an earlier paper1, it was mentioned that aspartic A. L. BACHARACH. acid is not present in the amino acid mixture. This H. E. GLYNN. erroneous conclusion is ascribable to the fact that, Glaxo Laboratories, Ltd., owing to the small amount of material available, the 56 Osnaburgh Street, determination was made from the solution from London, N.W.l. which ammonia had first been distilled off according Oct. 18. to van Slyke, in which process aspartic acid seems to • Proc. 6th Caw,. Cong. Phys. Pharm. Bio., Academy of Sciences be precipitated as a calcium salt. Press, Moscow and Leningrad, 101; 1935. The composition of the excreted amino acid mixture is very interesting in several respects.
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