Crystallization of goat β-lactoglobulin

Abstract

Beta-Lactoglobulin may be crystallized from goat milk by means of ammonium sulfate. The isoelectric point of the protein lies at pH 5.9 in sodium acetate buffer, I = 0.1. The electrophoretic behavior of the protein was studied at pH values ranging from 4.1 to 8.1. The protein appears homogeneous forming a symmetrical boundary at pH 4.15 and 5.6-8.1. An asymmetric boundary may be noted in the descending limb at about pH 4.6 and 5.1 in sodium acetate buffer, I =0.1. This asymmetry disappears on raising the concentration of the sodium acetate to an ionic strength of 0.2 pH 4.65. The goat beta-lactoglobulin was found to have a molecular weight of the same order as bovine beta-lactoglobulin (i.e. 37,100). S20 was 2.85 and D20 7.48 x 10-7.