New alpha s2-casein variant from caprine milk.

A new alpha s2-casein variant was isolated from goat milk by means of covalent chromatography. With gel electrophoresis at alkaline pH, the alpha s2-casein variant showed a double band with the highest anodic mobility amongst the casein components. The mobility of the isolated alpha s2-casein variant was similar to that occurring in three individual samples of whole casein. Two dimensional electrophoresis revealed a more pronounced heterogeneity of this protein. Developing the two dimensional plate with polyclonal antibodies obtained against the four main bovine casein fractions, we demonstrated that the variant in question belongs to the alpha s2-casein family. Since the alpha s2-casein fractions, immunospecifically developed, spread along two different zones on the gel, it was concluded that a heterozygous alpha s2-casein form was present in the sample.