title: Mechanism of degradation of LH-RH and neurotensin by synaptosomal peptidases.
abstract: The products of degradation of LH-RH and neurotensin by synaptosomes isolated from rat hypothalamus and cortex have been identified. LH-RH is cleaved at Tyr5-Gly6 and Pro9-Gly10 giving rise to LH-RH (1-5), LH-RH (6-10) and LH-RH (1-9). Neurotensin is cleaved at Arg8-Arg9, Pro10-Tyr11 and Ile12-Leu13, giving neurotensin (1-8), neurotensin (1-10), neurotensin (1-12) and neurotensin (9-13) as major products. While most of the peptidase activity is localized in the cytoplasmic fraction, a small but significant proportion is membrane bound. For LH-RH, the specificity of the membrane-bound activity is similar to that in the cytosol fraction; for neurotensin, the membrane fraction preferentially gives rise to the (1-10) and (1-11) peptides. The most potent inhibitors of the LH-RH and neurotensin degrading enzymes in synaptosomes are heavy metal ions (mercury and copper), p-chloromercuribenzoate and 1,10 phenanthroline.
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001711:Biotransformation; D003593:Cytoplasm / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D009496:Neurotensin / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism*; D051381:Rats; D013347:Subcellular Fractions / Q000378:metabolism; D013569:Synapses / Q000378:metabolism; D013570:Synaptic Membranes / Q000378:metabolism; D013574:Synaptosomes / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D007987:Gonadotropin-Releasing Hormone; D009496:Neurotensin; D007770:L-Lactate Dehydrogenase; D010447:Peptide Hydrolases