title: Enzyme immunoassay of angiotensin I.
abstract: A very sensitive and specific enzyme immunoassay has been developed for angiotensin I. Angiotensin I was coupled to beta-D-galactosidase by a novel cross-linking reagent, N-(meta-maleimidobenzoyloxy)succinimide. No decrease in the enzyme activity was observed during the coupling procedure. In the angiotensin I-beta-D-galactosidase conjugate, 0.39 mol immunoreactive angiotensin I/mol enzyme were present. A competitive assay with the enzyme-labeled angiotensin I was performed. Antibody-bound and free labeled antigen were separated from each other by the second antibody method, and the enzyme activity of the former was estimated. Using this assay, angiotensin I could be detected in the range of 1.2--50 pg. The sensitivity was 4.5-fold higher than that of the usual RIA. This assay distinguished clearly angiotensin I from angiotensin II, angiotensin III, and (Sar1, Ile8)-angiotensin II. The present method was applied to measure PRA in dogs; the results correlated fairly well with those obtained by the RIA (r = 0.94).
mesh_terms: D000803:Angiotensin I / Q000097:blood*; D000804:Angiotensin II; D000805:Angiotensin III; D000809:Angiotensins / Q000097:blood*; D000818:Animals; D004285:Dogs; D007124:Immunoenzyme Techniques; D011863:Radioimmunoassay; D012083:Renin / Q000097:blood; D014667:Vasopressins; D001616:beta-Galactosidase
chemical_list: D000809:Angiotensins; D014667:Vasopressins; D000804:Angiotensin II; D000805:Angiotensin III; D000803:Angiotensin I; D001616:beta-Galactosidase; D012083:Renin