Intestinal Dipeptidases

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Abstract
Human intestinal juice, collected at different levels by transintestinal intubation technique, has been studied in respect to its dipeptidase activities, using L-alanyl-L-glutamic acid, L-alanyl-L-proline and glycyl-L-leucine as substrates. Only L-alanyl-L-proline dipeptidase activity was generally observed in samples from the jejunal region. In contrast, juice collected from the ileal region mostly contained all the three dipeptidase activities. When their amounts in the intestinal juice were related to their amounts in the intestinal mucosa, the L-alanyl-L-glutamic acid activity and the glycyl-L-leucine activity showed relative figures of only 1-2%, while the L-alanyl-L-proline activity gave figures more equal to those observed in the mucosa. The significance of this marked difference between the L-alanyl-L-proline dipeptidase and the other two activities has been discussed and related to our present knowledge about the intestinal hydrolysis of the dipeptides.