Beitrag zum Problem des Vorkommens von Polypeptidasen im Blutserum und im Harn von Carcinomträgern, die Polypeptide zu spalten vermögen, in denen d- Aminosäuren enthalten sind

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Abstract
The polypeptides, d-leucyl-glycylglycine, 1-leucylglycylglycine, d-alanylglycylglycine and 1-alanylglycylglycine were prepared by coupling d- or 1-a-bromoisocapronyl chloride and d- or 1-a-bromopropionyl chloride with glycylglycine, followed by animation with 25% NH3. Glycyl-d-leucine and glycyl-1-leucine were formed by coupling bromoacetyl chloride with d- or 1-leucine. The reaction mixture consisted of 2.5 cc. M/10 polypeptide soln., 1 cc. M/5 phosphate buffer soln., and 1.5 cc. serum. The increase in acidity was detd. by titration of 2 cc. of the mixture with N/20 alcoholic KOH. Of 41 patients with carcinoma, the serum of 9 hydrolyzed d-leucylglycylglycine and d-alanylglycylglycine. It could not be shown that the presence of a d-peptidase in the serum of cancer patients was a regular occurrence. Of 49 patients without carcinoma, the serum of one patient hydrolyzed these polypeptides. Glycyl-d-leucine and d-alanyl-1-tryptophane were not hydrolyzed by serum of cancer patients. Various 1-polypeptides were readily hydrolyzed by the serum of all patients. When present, the d-polypeptidase was not injured by drying the serum in vacuo at room temp. and was excreted in the urine.

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