Rybarska-Stylínska J, Van Etten R L
Biochim Biophys Acta. 1979 Sep 12;570(1):107-17. doi: 10.1016/0005-2744(79)90205-5.
Antibodies against homogeneous rabbit liver arylsulfatase A (aryl-sulfatase sulfohydrolase, EC 3.1.6.1) were produced in a goat and the effects of these antibodies on the kinetic parameters of the enzyme have been studied. The results indicate that the binding of antibody to the enzyme does not alter the enzyme active site, since Km and -ki values are unaffected. However, a small reduction in the enzyme activity was observed as the result of a reduction of V in the enzyme-antibody complex. The binding of antibodies led to a change in the pH-rate profile, giving one broad pH optimum shifted toward higher pH value. The enzyme-antibody complex still showed the characteristic arylsulfatase A anomalous kinetics at pH 5.5, but the inactivation was significantly slower than for the native enzyme. As calculated from quantitative immuno-precipitation data, the native enzyme bound 5--7 molecules of IgG. The number of IgG molecules which bound to the turnover-modified enzyme was reduced to 3--4. The loss of antigenic determinants from the turnover-modified enzyme indicates that significant conformational changes occur during the turnover-induced modification, or that a covalent modification of residues present at the antigenic sites has occurred, or both.
在山羊体内产生了针对纯合兔肝芳基硫酸酯酶A（芳基硫酸酯硫酸水解酶，EC 3.1.6.1）的抗体，并研究了这些抗体对该酶动力学参数的影响。结果表明，抗体与酶的结合不会改变酶的活性位点，因为米氏常数（Km）和抑制常数（-ki）的值未受影响。然而，由于酶 - 抗体复合物中最大反应速度（V）降低，观察到酶活性有小幅下降。抗体的结合导致pH - 速率曲线发生变化，产生一个向更高pH值偏移的宽pH最佳值。酶 - 抗体复合物在pH 5.5时仍显示出特征性的芳基硫酸酯酶A异常动力学，但失活速度明显慢于天然酶。根据定量免疫沉淀数据计算，天然酶结合5 - 7个免疫球蛋白G（IgG）分子。与周转修饰酶结合的IgG分子数量减少到3 - 4个。周转修饰酶抗原决定簇的丧失表明，在周转诱导修饰过程中发生了显著的构象变化，或者抗原位点存在的残基发生了共价修饰，或者两者皆有。
