The nuclear magnetic resonance determination of the conformation of saccharides bound in subsite D of lysozyme

The binding of the trisaccharide (2-acetamido-2-deoxy-D-muramic acid)-β(1→4)-(2-aceta-mido-2-deoxy-D-glucosyl)-β(1→4)-(2-acetamido-2-deoxy-D-muramic acid) to subsites B, C, and D in lysozyme has been studied by 1H nuclear magnetic resonance methods. In particular, the coupling constant between H1 and H2 of the reducing saccharide bound in subsite D has been determined. The coupling constant for the bound saccharide indicates that the dihedral angle between C1 and C2 for the reducing saccharide is not significantly changed upon binding to lysozyme. This result is discussed in terms of other evidence for the role of distortion of the saccharide bound in subsite D in the lysozyme-catalyzed hydrolysis of cell wall oligosaccharides.