College of Food Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
J Sci Food Agric. 2012 Jun;92(8):1709-15. doi: 10.1002/jsfa.5536. Epub 2012 Jan 6.
γ-Aminobutyric acid (GABA) is a non-protein amino acid with bioactive functions for human health. Diamine oxidase (DAO, EC 1.4.3.6) is one of the key enzymes for GABA formation. In the present study, this enzyme was purified from 5 day germinated fava bean and its properties were investigated in vitro.
The molecular mass of the enzyme estimated by Sephadex G-100 gel filtration was 121 kDa. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) displayed a single band at a molecular mass of 52 kDa. The enzyme had optimal activity at 40 °C and retained its activity after being incubated at 30 °C for 30 min. It showed higher activity at pH 6.5 than at other pH values. The enzyme was significantly inhibited by Mg(2+), Cu(2+), Fe(3+), aminoguanidine, ethylene glycol tetraacetic acid (EGTA), ethylene diamine tetraacetic acid disodium salt (EDTA-Na(2)), L-cysteine and β-mercaptoethanol. The K(m) value of DAO was 0.23 mmol L(-1) for putrescine and 0.96 mmol L(-1) for spermidine. However, the enzyme did not degrade spermine.
DAO from germinated fava bean was purified. The optimal reaction temperature and pH of the enzyme were mild. The enzyme had higher affinity to putrescine than to spermidine and spermine.
γ-氨基丁酸（GABA）是一种具有生物活性的非蛋白氨基酸，对人体健康有益。二胺氧化酶（DAO，EC 1.4.3.6）是 GABA 形成的关键酶之一。本研究从 5 天发芽的蚕豆中纯化了这种酶，并在体外研究了其性质。
Sephadex G-100 凝胶过滤法估计该酶的分子量为 121 kDa。十二烷基硫酸钠聚丙烯酰胺凝胶电泳（SDS-PAGE）显示分子量为 52 kDa 的单一带。该酶在 40°C 时具有最佳活性，在 30°C 孵育 30 分钟后仍保持活性。其在 pH6.5 时的活性高于其他 pH 值。该酶被 Mg(2+)、Cu(2+)、Fe(3+)、氨基胍、乙二醇四乙酸（EGTA）、乙二胺四乙酸二钠盐（EDTA-Na(2)）、L-半胱氨酸和β-巯基乙醇显著抑制。DAO 对腐胺的 K(m)值为 0.23 mmol L(-1)，对亚精胺的 K(m)值为 0.96 mmol L(-1)。然而，该酶不能降解精胺。
从发芽的蚕豆中纯化了 DAO。该酶的最适反应温度和 pH 值较为温和。该酶对腐胺的亲和力高于亚精胺和精胺。
