Studies on the heterogeneity of crystallized β-lactoglobulin

Abstract

Measurements were made of the electrophoretic migration of beta-lactoglobulin under various conditions of concentration, pH and temperature. Evidence is obtained of the presence of 2 very similar chemical species, in proportions which may vary from one sample to another, and which can be separated only with great difficulty. One of these species associates reversibly to form a complex which migrates and sediments more rapidly than the simple material. Sedimentation suggests that this is a dimer. This association is strongly dependent on temperature and pH. Solubility measurements con-firm the heterogeneity of beta-lactoglobulin. The form of migration boundaries is discussed in the light of this conclusion. Previous data on the osmotic pressure of beta-lactoglobulin are discussed.