ENZYME-INHIBITOR COMPLEXES OF LYSOZYME WITH GLUCOSAMINE INHIBITORS - A MOLECULAR-DYNAMICS STUDY THROUGH H-2 NMR

H-2 relaxation measurements coupled with multiple specific H-2 labeling have provided insight into the molecular dynamics of N-acetyl-D-glucosamine (GlcNAc) inhibitors bound to lysozyme. Deuteron T1 and T2 data for the bound state of methyl alpha- and -beta-GlcNAc H-2-labeled in the glycosidic methyl and C2 positions have been derived from measurements at different enzyme/inhibitor ratios. Rotational correlation times calculated therefrom for the labeled sites indicate, in both cases, tight binding for the sugar ring (tau-b = 3.0 X 10(-9) s) accompanied by fast internal rotation, about one axis, of the glycosidic methyl groups (tau-r = 5.5-7.6 X 10(-11) s). The small but consistent difference in the rates of internal rotation for the alpha- and beta-anomeric inhibitors may be indicative of different solution structures of the enzyme-inhibitor complexes.