Subcellular localization in rat brain of angiotensin-related carboxypeptidase activity distinct from converting enzyme.
Whole brain synaptosomes contain both an isorenin activity and angiotensin-related carboxypeptidase activity. Further hydrolysis of des-Leu angiotensin I (AI-dL) occurs more slowly; hydrolysis of angiotensin II (AII) is negligible. Vasopressin and oxytocin but not vasotocin can inhibit angiotensin-related carboxypeptidase activity. Since AII has been shown to induce vasopressin secretion, this correlation suggests a feedback inhibition by vasopressin of this enzymatic cascade. Commercially available radioimmunoassays for AI and AII show a 3.4 and 6.0% crossreactivity, respectively. When the absolute concentration of AI-dL exceeded 500 ng/ml, both antibodies to AI and AII showed maximal displacement of radiolabel. This suggests that these antibodies may not distinguish between AI-dL from other peptides during immunocytochemistry.
Changaris
D G
DG
Department of Surgery (Division of Neurological Surgery), University of Louisville School of Medicine, Ky.
Lesousky
N W
NW
Miller
J J
JJ
Levy
R S
RS
D000803:Angiotensin I / Q000031:analogs & derivatives / Q000378:metabolism; D000804:Angiotensin II / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000201:enzymology*; D002268:Carboxypeptidases / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism*; D006868:Hydrolysis; D066298:In Vitro Techniques; D051381:Rats; D011919:Rats, Inbred Strains; D013347:Subcellular Fractions / Q000378:metabolism
D000804:Angiotensin II; C045857:angiotensin I, des-Leu(10)-; D000803:Angiotensin I; D002268:Carboxypeptidases; C055883:angiotensin-related carboxypeptidase