Peptidases of the peripheral chemoreceptors: biochemical, immunological, in vitro hydrolytic studies and electron microscopic analysis of neutral endopeptidase-like activity of the carotid body

摘要: The purposes of the present study are to identify and characterize major peptidase(s) that may be involved in inactivation neuropeptides mammalian carotid body. Measurements a number peptidase activities cell-free extract cat body using specific substrates inhibitors indicated previously identified neutral endopeptidase (NEP)-like activity [Kumar et al., Brain Res., 517 (1990) 341–343] is chemoreceptor tissue. NEP-like was further characterized monoclonal antibody human endopeptidase, EC 3.4.24.11. Immune blot analysis strong immunoreactivity toward calf bodies but weak cross-reactivity with rabbit Furthermore, western revealed presence 97-kDa protein minor 200-kDa protein. NEP form comparable 3.4.24.11 consistent its reported molecular weight suggesting structurally similar In order assess whether primary peptide degrading vitro hydrolysis studies substance P (SP) as model were performed. HPLC showed SP hydrolyzed maximally at pH 7.0 by peptidases formation SP(1–7) SP(1–8) stable intermediates. Inhibitors also inhibited SP-hydrolyzing Analyses extracts occurrence both rat although 2- 4-fold lower levels respectively than observed Immunoelectron microscopy NEP-specific associated intercellular region between type I cells cell clusters Taken together, results from this investigation demonstrate (EC 3.4.24.11) one endopeptidases which mediates degradation