[On the differentiation of aminopeptidases in urine by a synthetic tripeptide (author's transl)].

In contrast to findings in healthy people two aminopeptidases with alanine-specifity were found in urine samples of patients after allogenic kidney transplantation. The two aminopeptidases revealed different enzymatic and immunologic properties: one alanine-aminopeptidase (AAP) could be specifically inhibited by a synthetic Thr-Phe-Pro-(tertiary butyl) tripeptide, but was not immunoreactive against an antibody, raised against plasma membranes of human kidney tubule. The tripeptide however was not capable to inhibit the second AAP which exhibited immunoreactive precipitins against the antibody. The appearance of the latter AAP had a close relation to tubular damage during graft rejection episode.