Isolation from bovine liver mitochondria and characterization of three distinct carboxylic acid:CoA ligases with activity toward xenobiotics
作者:Donald A. Vessey、Jie Hu
DOI:10.1002/jbt.2570100608
日期:1995.10
was fractionated on a DEAE-cellulose column into four distinct acyl-CoA ligase fractions. First to elute was a 50 kDa short-chain ligase that activated only short-chain fatty acids. Next to elute were three ligases that had activity toward both medium-chain fatty acids and xenobiotic carboxylic acids; these were termed xenobiotic/medium-chain ligases (X-ligases) and labeled XL-I, XL-II, and XL-III, respectively
将线粒体冷冻/解冻裂解物在DEAE-纤维素柱上分离成四个不同的酰基-CoA连接酶馏分。首先洗脱的是一个仅激活短链脂肪酸的50 kDa短链连接酶。紧随其后的是三种对中链脂肪酸和异种羧酸都具有活性的连接酶。根据洗脱顺序,这些分别称为异种/中链连接酶(X-连接酶)并标记为XL-1,XL-II和XL-III。X-连接酶I,II和III的分子量约为。55,000、55,500和53,000。XL-III型没有最佳pH值。从pH值7.0开始,速率稳定增加。XL-I和XL-II在以苯甲酸酯为底物时表现出相同的行为,但在中链脂肪酸中,两种形式的pH最佳均为8.8。三种X连接酶的底物特异性不同。XL-1是主要的烟酸活化形式,对苯甲酸酯的Km最低。XL-II形式是唯一可测量的水杨酸盐活性的形式,尽管它的含量极低。XL-III是唯一的2,4,6,8-癸二烯酸活化形式,也是主要的中链脂肪酸活化形式。通过比较底物特