Porter D J, Bright H J
J Biol Chem. 1976 Oct 10;251(19):6150-3.
N-Chloro-D-leucine is an irreversible inhibitor or D-amino acid oxidase on a time scale of seconds. Studies with N-[36C]chloro-D-leucine, N-chloro-D-[1-14C]leucine and N-chloro-D-[4,5-3H]leucine show that the modified enzyme has been chlorinated at a site, or sites, on the apoenzyme. The 36Cl measurements agree with titrations of catalytic activity in showing that two chlorine equivalents are incorporated per active site flavin. Kinetically, the interaction with N-chloro-D-leucine behaves in a manner which is consistent with consecutive chlorinations of an amino acid residue, or residues, in the active site region by the first 2 molecules of N-chloro-D-leucine to be processed by the enzyme. The effect of chlorination of the enzyme on the steady state parameters for oxidation of D-alanine is entirely explained by a single perturbation, namely, a 1000-fold reduction in the specific rate of flavin reduction as measured directly by rapid reaction techniques.
N-氯-D-亮氨酸在数秒的时间尺度上是D-氨基酸氧化酶的不可逆抑制剂。使用N-[36C]氯-D-亮氨酸、N-氯-D-[1-14C]亮氨酸和N-氯-D-[4,5-3H]亮氨酸进行的研究表明，修饰后的酶在脱辅基酶的一个或多个位点上发生了氯化。36Cl测量结果与催化活性滴定结果一致，表明每个活性位点黄素结合了两个氯当量。从动力学角度来看，与N-氯-D-亮氨酸的相互作用表现出的方式与活性位点区域中的一个或多个氨基酸残基被酶处理的前两个N-氯-D-亮氨酸分子连续氯化相一致。酶的氯化对D-丙氨酸氧化的稳态参数的影响完全可以由一个单一的扰动来解释，即通过快速反应技术直接测量的黄素还原比速率降低了1000倍。
