Preliminary X-ray data for some new crystalline forms of β-lactoglobulin and hen-egg-white lysozyme

Abstract

In the course of an investigation of the structure of protein crystals in progress in this Laboratory, a new crystalline form of fl-lactoglobulin and three new forms of salts of egg-white lysozyme have been studied. Preliminary X-ray data for these crystals are listed in Table l, together with pertinent data published by earlier workers which are included for comparison. Values for the density and water content of most of the new forms are also listed. Densities were determined by flotation in benzene-bromobenzene mixtures, special care being taken to avoid interaction between the crystal and the flotation medium. The water content was taken as the weight lost by the wet crystals when placed in an oven at 100 °C. for 20 minutes; it is so designated in the table. It is felt that the error of the data on unit-cell dimensions is less than 1%, the error of the density measurements is less than 3 %, and the error of the amount of water removed at 100 °C. is about 10%.