The Role of Distortion in the Lysozyme Mechanism
This extract was created in the absence of an abstract.
Excerpt
One of the most fascinating features of the mechanism proposed by Phillips and co-workers (Blake et al., 1967a, b; Phillips, 1966) for the cleavage of oligosaccharides by lysozyme is the distortion of the saccharide bound in subsite D into a half-chair conformation. This mechanism is based upon X-ray crystallographic studies of the non-productive complex of lysozyme with chitotriose, GlcNAc-β(1 → 4)-GlcNAc-β(1 → 4)GlcNAc, (bound in subsites A, B, C) and model building. The involvement of substrate distortion in the proposed mechanism is supported by several studies (Chipman et al., 1967; Chipman and Sharon, 1969; Chipman, 1971; Johnson et al., 1968; Rupley and Gates, 1967) which estimate that the contribution to the free energy of binding of oligosaccharides from the saccharide bound in subsite D is unfavorable by 3–6 kcal mole−1. This is exemplified by a comparison of the binding constants for GlcNAc-β(1 → 4)-MurNAc-β(1 → 4)GlcNAc (KA = 2.8 ×...
