Biological Role of α-Lactalbumin: A Review

Abstract

The biological role of [alpha] -lactal-bumin was elucidated recently. [alpha]-Lactalbumin is one of 2 proteins required for the lactose synthetase enzyme, the enzyme responsible for the biosynthesis of lactose. This enzyme requires an A protein, a B protein ([alpha]-lactalbumin), substrates and metal for activity, [alpha] -Lactalbumin, by itself, does not have any catalytic activity and hence the elucidation of its function came about in an indirect manner. [alpha] -Lactalbumins isolated from various sources, have about the same activity when assayed with bovine A protein in the lactose synthetase assay. However, [alpha]-lactalbumin from ruminants will react with antisera to bovine [alpha]-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 [alpha] -lactalbumin and hens egg-white lysozyme suggesting that both proteins arose from a common ancestral gene.