Abstract
By ion exchange chromatography on DEAE-cellulose in the presence of 4 M urea, bovine κ-casein A was fractionated into 9 subcomponents, all of which were identified as κ-casein from immunological analyses. The microheterogeneity of the subcomponents was explained by stepwise increase of their carbohydrate contents (0-4mol/mol of GalNAc, and 0-8mol/mol of NANA). The micelle-stabilizing ability of κ-casein subcomponents increased with the increase of their carbohydrate contents: the carbohydrate rich subcomponent 7 possessed twice the stabilizing ability of the carbohydrate free subcomponent 1. The sensitivity of synthetic casein micelle composed of κ-casein subcomponents and αS1-casein to the wheat germ lectin-induced aggregation also increased with the increase of their NANA contents.
