Substituent effect on lysozyme-catalysed hydrolysis of some beta-aryl di-N-acetylchitobiosides.
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ABSTRACT: 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.
SUBMITTER: Tsai CS
PROVIDER: S-EPMC1184925 | biostudies-other | 1969 Sep
REPOSITORIES: biostudies-other
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