Molecular dynamics through 2H spin-lattice relaxation time measurements with an enzyme-inhibitor complex: lysozyme and methyl N-acetyl glucosaminides.

Deuteron spin-lattice relaxation times of specifically labelled methyl N-acetyl-D-glucosaminides associated to lysozyme were measured from 1H and 2H NMR spectra through bandshape analysis and FT inversion-recovery technique, respectively. Model calculations were carried out in order to assess the limits of the extreme narrowing approximation for the systems studied. Rotational correlation times of the acetamido methyl groups were analyzed in terms of anisotropic overall reorientation combined with internal rotation. The acetamido methyl group undergoes fast internal rotation in the alpha-glycoside complex about an axis nearly parallel with the major ellipsodial axis of lysozyme. More rotational freedom is likely to occur in the beta-glycoside complex.