Liver monoamine oxidase in the obese-hyperglycaemic (ob/ob) mouse.
1. The specific activity of monoamine oxidase was found to be greater in liver mitochondria from ob/ob mice than from lean mice. The activities of marker enzymes were similar in both tissues. 2. Experiments with various substrates (5-hydroxytryptamine, benzylamine and tyramine) and inhibitors (clorgyline and deprenyl) indicated that, unlike rat liver mitochondria, mouse liver mitochondria contain a predominance of the B-form of monoamine oxidase. 3. The Km values for lean and ob/ob mice were the same for any given substrate and were in the increasing order 5-hydroxytryptamine less than tyramine less than benzylamine. Vmax. was approximately 50% greater in obese than in lean mice. 4. Extraction of liver mitochondria with acetone/water or acetone/water/NH3 to remove lipids decreased the enzyme activity relatively more in obese- than in lean-mice preparations, but residual activity was the same in both preparations.
D000818:Animals; D003010:Clorgyline / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D007700:Kinetics; D050356:Lipid Metabolism; D008297:Male; D051379:Mice; D008820:Mice, Obese; D008930:Mitochondria, Liver / Q000201:enzymology*; D008995:Monoamine Oxidase / Q000378:metabolism*; D008996:Monoamine Oxidase Inhibitors / Q000378:metabolism; D051381:Rats; D012642:Selegiline / Q000494:pharmacology; D013379:Substrate Specificity
D008996:Monoamine Oxidase Inhibitors; D012642:Selegiline; D008995:Monoamine Oxidase; D003010:Clorgyline