title: Twin studies and substrate differences in platelet monoamine oxidase activity.
abstract: Monoamine oxidase activity was measured in blood platelets of 7 pairs of identical (MZ) twins and a similar number of age- and sex-matched control pairs. Mean intrapair difference in platelet MAO activity was significantly smaller (0.01 less than p less than 0.025) in MZ compared to controls. Kinetic studies of the enzyme revealed mean Km value of 1.0 x 10(-5) mol/l for tryptamine. Platelet MAO activity is higher in women than in men.
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001792:Blood Platelets / Q000201:enzymology*; D005260:Female; D006801:Humans; D008297:Male; D008995:Monoamine Oxidase / Q000097:blood* / Q000235:genetics; D011247:Pregnancy; D012737:Sex Factors; D013379:Substrate Specificity; D014363:Tryptamines; D014427:Twins; D014430:Twins, Monozygotic; D014439:Tyramine
chemical_list: D014363:Tryptamines; D008995:Monoamine Oxidase; D014439:Tyramine