Substituent effect on lysozyme-catalysed hydrolysis of some beta-aryl di-N-acetylchitobiosides.
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.
D002686:Chitin / Q000138:chemical synthesis / Q000378:metabolism; D003903:Deuterium; D004583:Electrons; D007700:Kinetics; D009113:Muramidase / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism*
D011134:Polysaccharides; D002686:Chitin; D003903:Deuterium; D009113:Muramidase
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