in plants, γ-aminobutyric acid (gaba) is synthesized by polyamine degradation pathway besides gaba shunt. aminoguanidine (ag) is a specific inhibitor of the key enzyme (diamine oxidase, dao) for gaba formation in polyamine degradation pathway. in this study, ag was applied to study the functions of polyamine degradation pathway on growth and gaba accumulation in germinating fava bean under hypo...

Diamine oxidase was previously measured in human pregnancy serum with putrescine or histamine as substrate. We have now documented the presence of spermidine oxidase activity in pregnancy serum by means of a specific radioactive assay with l '4Clspermidine as substrate and Dowex 50 cation-exchange chromatography to separate products from substrate. The apparent Km of a partially purified prepar...

We have recently presented evidence that diamine oxidase is rcsponsiblc for a portion of the metabolism of histamine in several species (1, 2). This evidence is largely based on the alteration of histamine metabolism produced by compounds which are known to inhibit diamine oxidase in vitro. The inhibitors used were isonicotinylhydrazine (3) and aminoguanidine. The latter is reported to be the m...

Increased plasma histamine levels were associated with significantly lowered diamine and type B monoamine oxidase activities in platelet-rich plasma of atopic eczema (AE) patients. The diamine oxidase has almost normal cofactor levels (pyridoxal phosphate and Cu(2+)) but the cofactor levels for type B monoamine oxidase (flavin adenine dinucleotide and Fe(2+)) are lowered. The biogenic amines pu...

Diamine oxidase is continuously released from the intestinal mucosa and carried to the circulation by the lymphatics. The effect of nutrients on this release was examined. Rats were prepared with duodenal and intestinal lymph cannulas. Test mixtures of lipid emulsions containing triolein, oleic acid, or tricaprylin and solutions of carbohydrate and protein were infused into the duodenum. The en...

1. The purification of monoamine oxidase and diamine oxidase from normal human term placental tissue is described. 2. The properties of these enzymes are reported and compared with the properties of unpurified human pregnancy plasma. 3. This comparison shows that the amine oxidase of pregnancy plasma has properties corresponding to purified placental diamine oxidase, suggesting a placental orig...

Diamine oxidase (histaminase) is an enzyme found in high concentrations in the intestinal mucosa of humans and other mammalian species. We investigated whether plasma and mucosal levels of diamine oxidase activity reflect both the maturational status of the mucosa during its development in the newborn rate and the degree of mucosal damage during its injury in the adult rat. Litter mates were re...

Plasma diamine oxidase levels were assayed in 66 patients who presented with pregnancy complicated by threatened abortion. Levels within the normal range were associated with continuing pregnancies, whereas levels below the normal range were associated with subsequent abortion. Among those patients in whom gestation was greater than eight weeks, 66.6% of diamine oxidase levels correctly predict...