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This enzyme dissolves certain bacteria by cleaving polysaccharides in their cell walls so that the bacterial cells burst. The active site accommodates six sugar residues (ABCDEF) and breaks a bond between sugars D and E. This bond lies near Glu-35 and Asp-52. Glu-35 (non-ionized) donates a proton to C-1 of ring D creating a positive charge there. This positive charge on C-1 (carbonium ion) is stabilized by Asp-52. As a result of protonation the C--O bond is split. Probably ring D is sterically distorted so that it resembles the transition state during the enzyme reaction.
Phillips, D. C., Sci. Amer 215 (5) (1965) 78; Blake, C. C. F., Johnson, L. N., Mair, G. A., North, A. C. T., Phillips, D. C. and Sarma, V. R., Proc. Roy. Soc. B167 (1967) 378; Blake, C. C. F., Mair, G. A., North, A. C. T., Phillips, D. C. and Sarma, V. R., Proc. Roy. Soc. B167 (1967) 365; Phillips, D. C., Proc. Natl. Acad. Sci. USA 57 (1967) 493; Imoto, T., Johnson, L. N., North, A. C. T., Phillips, D. C. and Rupley, J. A., in P. B. Boyer (ed.), The Enzymes , Vol. VII, 3rd edition, p. 665, New York, London and San Francisco, Academic Press (1972); Artymiuk, P. J. and Blake, C. C. F., J. Mol. Biol . 152 (1981) 737.
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