Raftery, M. A. and Dahlquist, F. W. and Chan, S. I. and Parsons, S. M. (1968) A Proton Magnetic Resonance Study of the Association of Lysozyme with Monosaccharide Inhibitors. Journal of Biological Chemistry, 243 (16). pp. 4175-4180. ISSN 0021-9258 http://resolver.caltech.edu/CaltechAUTHORS:RAFjbc68
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It has been shown that the acetamido methyl protons of N-acetyl-d-glucosamine undergo a chemical shift to higher fields in their proton magnetic resonance spectrum when the inhibitor is bound to lysozyme. The observed chemical shift in the presence of the enzyme is different for the agr- and ß-anomeric forms of 2-acetamido-2-deoxy-d-glucopyranose indicating either a difference in the affinity of the anomeric forms for lysozyme or different magnetic environments for the methyl protons in their enzyme-bound state. That the agr- and ß-anomeric forms of GlcAc bind to lysozyme in a competitive fashion was indicated by observing the proton magnetic resonance spectra in the presence of 2-acetamido-d3-2-deoxy-agr-d-glucopyranose. The methyl glycosides, methyl-agr-GlcAc and methyl-ß-GlcAc, were also shown to bind competitively with both anomers of GlcAc. Quantitative analysis of the chemical shift data observed for the association of GlcAc with lysozyme was complicated by the mutarotation of GlcAc between its agr- and ß-anomeric forms. However, in the case of the methyl glucosides, where the conformation of each anomer is frozen, it was possible to analyze the chemical shift data in a straightforward manner, and the dissociation constant as well as the chemical shift of the acetamido methyl protons of the enzyme-inhibitor complex was determined for both anomers. The results indicate that the two anomers of methyl-GlcAc bind to lysozyme with slightly different affinities but that the acetamido methyl groups of both anomers experience identical magnetic environments in the enzyme-inhibitor complex.
|Additional Information:||Copyright © 1968 by the American Society for Biochemistry and Molecular Biology. (Received for publication, February 2, 1968) Contribution 3645 from the Gates and Crellin Laboratories of Chemistry, California Institute of Technology. This research was supported by United States Public Health Service Grants GM-14452-01 and GM-14523-02. [F.W.D. and S.M.P. were] National Institutes of Health Trainee[s] 1967-1968. [S.I.C. was an] Alfred P. Sloan Fellow. A preliminary account of the work described here was presented at the Gordon Research Conference on Proteins, New Hampton School, New Hampshire, June 27, 1966.|
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