Use of a monoclonal antibody for comparative studies of monoamine oxidase B in mitochondrial extracts of human brain and peripheral tissues.
Monoamine oxidase B (MAO B; EC 1.4.3.4) activity in detergent extracts of mitochondria from autopsy brain (gray matter and medulla), liver, lung, and kidney from a single individual and from pooled, human platelets could be immunoprecipitated by a monoclonal anti-human platelet MAO B antibody (MAO-1C2) in combination with appropriate secondary reagents. MAO A activity, which was detected in brain, liver, lung, and kidney, was not immunoprecipitated under the same conditions. All MAO B-containing extracts, regardless of tissue source, inhibited immunoprecipitation of [3H]pargyline-labeled human platelet MAO, and the shapes of the inhibition curves were identical. The concentration of immunologically detectable MAO B protein in the extracts was estimated from immunoprecipitation competition data by reference to a standard curve relating observed inhibition of immunoprecipitation to the concentration of catalytically active platelet MAO added (estimated from [3H]pargyline binding data). MAO B protein concentrations measured by this radioimmunoassay were similar to concentrations of active MAO B as measured by pargyline binding. These results demonstrate that in the brain and peripheral tissues studied, molecules with MAO B activity share a unique antigenic determinant and similar catalytic efficiency. They also extend previous observations that MAO B molecules extracted from mitochondria bear an antigenic determinant which is not present on MAO A molecules. These results demonstrate the validity of a new competitive radioimmunoassay for active plus inactive MAO B concentration in human platelet extracts and extracts of mitochondria from human tissues. This radioimmunoassay should complement [3H]pargyline binding assays and enzyme activity assays in studies designed to clarify the mechanisms of genetic, disease, and treatment factors which lead to differences in MAO B function among individuals.
D000328:Adult; D000911:Antibodies, Monoclonal; D001792:Blood Platelets / Q000201:enzymology; D001921:Brain / Q000201:enzymology*; D011232:Chemical Precipitation; D000939:Epitopes; D006801:Humans; D007120:Immunochemistry; D066298:In Vitro Techniques; D007668:Kidney / Q000201:enzymology; D008168:Lung / Q000201:enzymology; D008297:Male; D008928:Mitochondria / Q000201:enzymology*; D008930:Mitochondria, Liver / Q000201:enzymology; D008995:Monoamine Oxidase / Q000276:immunology / Q000378:metabolism*; D011863:Radioimmunoassay
D000911:Antibodies, Monoclonal; D000939:Epitopes; D008995:Monoamine Oxidase