Lysozyme: a model enzyme in protein crystallography.

摘要: The review concentrates on the crystal structure results from several protein crystallography laboratories three different lysozymes, type-c lysozymes such as hen egg-white lysozyme (HEWL), type-g lysozyme, goose (GEWL), and T4 bacteriophage (T4L). crystallographic studies HEWL in forms have shown that molecule is relatively rigid with residues of active site Glu35 Asp52 adopting almost identical conformations all structures species variants. NMR also confirm presence a similar conformation solution. All enzymes, HEWL, GEWL T4L are composed two domains, one predominantly alpha-helical smaller domain mainly beta-sheet nature. general acid/general base residue each (Glu35 Glu73 Glu11 T4L) contributed by larger domain. domains contribute an aspartate to their respective sites, which likely involved electrostatic stabilization oxycarbonium ion intermediate D sugar hydrolytic pathway oligosaccharides. There no analogous carboxylate group although minor conformational changes could position or other Asp86 Asp97 for role. binding substrate analogues, transition state mimics oligosaccharide products hydrolysis greatly our understanding proteins. observed subtle differences free vs bound these enzymes best described narrowing clefts inhibitors. Details interactions those lining three-enzymes sites A, B, C presented discussed. Oligosaccharides (GlcNAc)n alternating MurNAc-GlcNAc-MurNAc been determined at high resolution. These catalytic mechanism glycosidase activity. currently accepted view this discussed review.