The catalytic action of lysozyme.
2015-11-19T08:44:55Z (GMT) by
In Chapter 1, the physical properties and three dimensional configuration of hens' egg-white lysozyne are reviewed. This is followed by a discussion of lysozyme-chitin oligosaccharide interactions, both in the crystal and in solution, and of the kinetic studies of the lysozyme catalysed hydrolysis of low molecular- weight substrates. Recent developments in glycoside hydrolysis and neighbouring group reaction are discussed in the context of general mechanisms of enzyme action and finally the mechanisms proposed for the action of lysozyme are discussed. A new procedure for the preparation and separation of chitin oligosaccharides is described in Chapter 2, and the advantages this method affords over previously reported procedures are discussed. Also in this Chapter the determination of the pH-dependence of the Michaelis-Menten parameters for the lysozyme catalysed hydrolysis of penta-N-acetyl chitopentaose is described. The results are discussed in relation to the mechanisms proposed for the catalytic action of lysozyme. Chapter 3 contains a fluorine nuclear magnetic resonance study of the binding of N-trifluoroacetyl D glucosamine to lyso- zyme. The results indicate that the ?-anomer is hound much less strongly than the ?-anomer. The application of fluorine containing compounds as probes for the binding cleft of lysozyme are discussed. In Chapter 4, o-carboxyphenyl 2-acetamido-2-deoxy ?-D gluco-pyranoside is demonstrated to undergo intramolecularly-catalysed hydrolysis sixteen times faster than that of o-carboxyphenyl ?-D glucopyranoside. This is attributed to nucleophilic catalysis by the unionized trans-acetamido group, which acts in concert with intramolecular general acid catalysis. A small buffer effect is also observed in the hydrolysis of this compound, the reasons for which are discussed. In addition, the methanolysis of o-carboxyphenyl 2-acetamido- 2-deoxy ?-D glucopyranoside is shown to proceed with greater than 90% retention of configuration. Finally, Chapter 5 contains a computer program to determine the initial velocity of an enzymically catalysed reaction and one to determine the adjustable parameters of the Michaelis-Menten equation by a least squares method.