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Amine oxidases (AO) are a group of enzymes that catalyze oxidative deamination of various amines and thus are of potential use in analytical applications. Amine oxidase from five-day-old Vigna mungo L. seedlings (VAO) was purified using ammonium sulfate fractionation and Q-Sepharose chromatography to 544 purification folds with 65% yield. VAO apparently is a homodimer with denatured molecular weight of 73 kDa. This enzyme is relatively stable in a pH range of 6.0 to 8.0 and at temperature below 40°C with a complete activity loss upon storage at pH 4.0 or temperature over 60°C (1 h). Kinetics studies of VAO with putrescine, cadaverine, histamine, and tyramine showed k cat /K m values of 2.54×10 7 , 6.73×10 6 , 2.65×10 5 , and 3.31×10 3 M-1 s-1 , respectively, with undetectable catalytic activity toward tryptamine. VAO was partially inhibited by ethylenediaminetetraacetic acid (EDTA) and completely inhibited by phenylhydrazine, suggesting it is likely a member of copper-containing AO family.

An extracellular L-glutamate oxidase (GLOD) was purified from soil-isolated Streptomyces sp 18G. The enzyme had a molecular weight of approximately 120,000 and consisted of two identical subunits, each with a molecular weight of 61,000. The isoelectric point was pH 8.5 and the enzyme had an optimal pH between 7.0-7.4. GLOD showed the maximum activity at 37ºC. The GLOD activity was stable at pH ranging from 6.5 to 7.0 for 1 hr. Among 21 amino acids tested for substrate specificity, L-glutamate was almost exclusively oxidized. D-glutamate and L-aspartate were oxidized but only to extents of 0.79% and 0.53%, respectively.