Enzymes immobilized as crystals. Hydrogen isotope exchange of crystalline lysozyme.

Immobilization of enzymes by crystallization and subsequent cross-linking provide structures characterized by a regular three-dimensional molecular arrangement and a high packing density. Compared to randomly immobilized enzymes, such structures permit more detailed analysis of the variations in kinetic properties arising from the three-dimensional network or perturbations of the molecular conformations. To obtain information on the effect of crystallization on the dynamic properties of the folded peptide chain in an enzyme molecule, hydrogen exchange rates were measured for both dissolved and crystalline lysozyme over a wide range of pH. Using this method, which reflects molecular oscillations between closely related conformations, no differences were detected between lysozyme in crystalline and dissolved state.