The distribution of impurities in lysozyme crystals

The effective distribution coefficient, KIeff, of turkey egg white lysozyme into host hen egg white lysozyme crystals was measured for varying levels of relative supersaturation, impurity concentrations and temperatures. Turkey egg white lysozyme served as a test impurity of high homology to hen egg white lysozyme. KIeff increased with increasing host protein concentration and temperature, consistent with a kinetically controlled incorporation process. The principles of slow crystal growth rate to limit impurity incorporation were applied to a commercial source of lysozyme with concomitant improvement in purity of re-crystallized protein.