Structures of triclinic mono- and di-N-acetylglucosamine: lysozyme complexes--a crystallographic study.

N-acetylglucosamine and di-N-acetylglucosamine bind to lysozyme in the triclinic crystal form. Attempts to bind tri-N-acetylglucosamine were unsuccessful. Difference syntheses showed both GalNAc³ and di-GalNAc to be bound as the β-anomers, and revealed shifts in the positions of some of the lysozyme atoms. As was found in the binding studies with tetragonal lysozyme, the side chain of Trp62 moved toward the bound inhibitor. The carbonyl oxygen atom of Ala107 appeared to shift slightly, but there was no suggestion of movement in the lobes of the molecules as was evident in the tetragonal crystals.