Substituent effect on lysozyme-catalysed hydrolysis of some beta-aryl di-N-acetylchitobiosides.
Substituent effect on lysozyme-catalysed hydrolysis of some beta-aryl di-N-acetylchitobiosides.
复制标题
取代基对溶菌酶催化某些 β-芳基二-N-乙酰壳二糖苷水解的影响。
DOI：
10.1042/bj1140529
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发表时间：
1969
期刊：
影响因子：
--
通讯作者：
S. C. Subbarao
中科院分区：
文献类型：
--
作者：
C. Tsai;J. Tang;S. C. Subbarao
本文报道了溶菌酶催化水解几种β -芳基二n -乙酰壳聚糖的动力学测量，其中一些是首次合成的。45度时的催化速率常数k（cat.）产生了一个弯曲的Hammett图（上凹），delta - tah（双匕首）和delta - tas（双匕首）的图有一个明显的断裂。具有吸电子基团的底物表现出动力学氘同位素效应(k（H) (cat)）。/ k (D)(猫)。)，而那些有供电子基团的则没有这种同位素效应。结果表明，这两种类型的衬底具有不同的运行机制。
Measurements are reported on the kinetics of the lysozyme-catalysed hydrolysis of several beta-aryl di-N-acetylchitobiosides, some of which have been synthesized for the first time. The catalytic rate constants (k(cat.)) at 45 degrees yield a curved Hammett plot (concave up) and the plot of DeltaH(double dagger) versus DeltaS(double dagger) has a sharp break. Substrates with electron-withdrawing groups exhibit a kinetic deuterium isotope effect (k(H) (cat.)/k(D) (cat.)), whereas those with electron-donating groups show no such isotope effect. The results suggest the operation of different mechanisms for the two types of substrates.