Genetic Polymorphism in Caseins of Cow's Milk. IV. Isolation and Properties of β-Caseins A, B, and C

A convenient method is presented for obtaining the genetic variants of B-casein of high purity utilizing DEAE-cellulose chronmtography in the presence of 3.3 ~ urea as a dissociating agent. Furthermore, the separation of heterozygous mixtures of the B-casein variants may be accomplished with column chromatography by simple manipulation of salt elution gradients. B-Caseins A, B, and C contained 15.18, 15.33, and 15.45% nitrogen, respectively, and 0.59, 0.57, and 0.50% phosphorus. The genetic forms of B-caseins may be conveniently identified by their relative electrophoretic mobilities on starch-gel and polyacrylanfide-gel.