High enkephalyl peptide degradation, due to angiotensin-converting enzyme-like activity in human CSF.

The metabolism of enkephalin peptides was studied in human cerebrospinal fluid. The degradation rates of (Leu)-enkephalin and (Leu)-enkephalin-Arg6 were compared and the latter was degraded at a 10-fold higher rate. The major enzyme activity was investigated by Mr determination and inhibition experiments, showing marked similarity with angiotensin-converting enzyme.