Evidence for thiol-dependent metallo-endopeptidase involved in degradation of luteinizing hormone-releasing hormone in glioma cells.

An endopeptidase generating a peptide comprised of the first five amino acids of luteinizing hormone-releasing hormone (LHRH) was isolated form the membranes of glioma C6 cells by a procedure including Brij extraction, p-mercuribenzoate-Sepharose chromatography, and Mono Q high-performance liquid chromatography. The molecular weight of the enzyme was estimated to be 64,000. The glial enzyme shows a similar inhibitor susceptibility to that of the enzyme of neuronal origin, and also to that of endopeptidase-24.15 (EC 3.4.24.15). Angiotensin-converting enzyme (EC 3.4.15.11) is suggested to be involved in the secondary cleavage of LHRH by the glioma cells.