for NADP(H) over NAD(H) at a physiological pH of 7.4. In the NADPH-linked reduction, 3HBD showed broad substrate specificity for a variety of quinones, ketones and aldehydes, including 3-, 17- and 20-ketosteroids and prostaglandin D(2), which were converted to 3alpha-, 17beta- and 20alpha-hydroxysteroids and 9alpha,11beta-prostaglandin F(2), respectively. Especially, alpha-diketones (such as isatin
3-羟基己异
巴比妥脱氢酶(3HBD)催化将
NAD(P)(+)链接的3-羟基己异
巴比妥氧化为3-羟基己异
巴比妥。该酶被认为是异
生物醇和某些羟基类
固醇的
脱氢酶,但其生理功能仍然未知。我们已经纯化了兔3HBD,分离了其cDNA,并检查了其对辅酶和底物的特异性,反应方向性和组织分布。3HBD是醛
酮还原酶(AKR)超家族的成员(AKR1C29),并且在7.4的生理pH值下,
NADP(H)优于
NAD(H)。在与
NADPH相关的还原反应中,3HBD对多种醌,
酮和醛(包括3-,17-和20-
酮类固醇和
前列腺素D(2))显示出广泛的底物特异性,它们被转化为3alpha-,17beta-和20alpha -羟基类
固醇和9alpha,11beta-
前列腺素F(2),分别。特别是,α-二
酮(如isatin和diacetyl)和脂质过
氧化衍生的醛(如4-oxo-和4-hydroxy-2-nonenals)是显示低K(m)值(0