Small-angle X-ray scattering study of the influence of solvent replacement (from H2O to D2O) on the initial crystallization stage of tetragonal lysozyme

The composition of lysozyme solutions in D 2 O under conditions favorable for the formation of tetragonal crystals has been investigated at different protein concentrations by small-angle X-ray scattering using the synchrotron radiation. In addition to lysozyme monomers, dimeric and octameric species are found in the crystallization solutions; the octamer content increases with an increase in the protein concentration. A comparison of the data with those obtained under similar conditions but with H 2 O used as a solvent has shown that the replacement of light water with heavy one leads to increase of octamer volume fraction in solution.