title: Kinetic-controlled hydrolysis of Leu-Val-Val-hemorphin-7 catalyzed by angiotensin-converting enzyme from rat brain.
abstract: Leu-Val-Val-hemorphin-7 (LVV-H7, LVVYPWTQRY), an opioid peptide, was found to be hydrolyzed sequentially by rat brain angiotensin-converting enzyme (ACE) in three steps through dipeptidyl carboxypeptidase activity. The kinetic constants evaluated were in order of: k(1) (0.19 min(-1))>>k(2) (0.0008 min(-1)) approximately k(3) (0.0006 min(-1)) in 10 mM NaCl at pH 7.5 giving rise to LVV-H5 almost quantitatively. The decapeptide was noted to be hydrolyzed 164- and 346-fold more efficiently than angiotensin I (Ang I) in k(cat) and kcat/Km values, respectively, at their optimal conditions. The kinetic-controlled preferential action of the brain enzyme on LVV-H7 is suggestive of its multiple roles in vivo.
mesh_terms: D000465:Algorithms; D000595:Amino Acid Sequence; D000803:Angiotensin I / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000201:enzymology*; D002384:Catalysis; D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid; D010450:Endopeptidases / Q000378:metabolism; D004789:Enzyme Activation; D008401:Gas Chromatography-Mass Spectrometry; D006454:Hemoglobins / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis / Q000187:drug effects; D007700:Kinetics; D008297:Male; D008970:Molecular Weight; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism*; D051381:Rats; D020539:Sequence Analysis, Protein; D012965:Sodium Chloride / Q000494:pharmacology; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013737:Testis / Q000201:enzymology
chemical_list: D006454:Hemoglobins; D010446:Peptide Fragments; D012965:Sodium Chloride; C074309:LVV-hemorphin-7; D000803:Angiotensin I; D010450:Endopeptidases; C020071:dipeptidyl carboxypeptidase; D007703:Peptidyl-Dipeptidase A