Biological Role of α-Lactalbumin: A Review

Abstract

The biological role of α-lactalbumin has been elucidated recently. It is one of two proteins required for the lactose synthetase enzyme, the enzyme responsible for the biosynthesis of lactose. This enzyme requires an A protein, a B protein (α-lactalbumin), substrates and metal for activity. α-Lactalbumin, by itself, does not have any catalytic activity and, hence, the elucidation of its function came about in an indirect manner. α-Lactalbumins isolated from various sources have about the same activity when assayed with bovine A protein in the lactose synthetase assay. However, α-lactalbumin from nonruminant sources will not react with antisera to bovine α-lactalbumin. Such studies indicate that the immunological binding sites and enzymic catalytic sites are distinct. Recent work also has indicated a high degree of homology in the amino acid sequence between bovine α-lactalbumin and hen's egg-white lysozyme, suggesting that both proteins arose from a common ancestral gene. © 1968, American Dairy Science Association. All rights reserved.