The enzymatic synthesis of sialyl-lactose

Abstract

Sialyl-lactose (SL) was first isolated from lactating rat mammary gland by Trucco and Caputto (1954). In subsequent extensive studies on milk oligosaccharides, Kuhn and coworkers ( Kuhn and Brossmer, 1958 and Kuhn, 1959) obtained two isomers of SL from human milk, one being identical to SL from bovine colostrum. Bovine SL was shown to be N-acetylneuraminyl-(2 --> 3)-[beta]-D-galactopyranosyl-(1 --> 4)-D-glucose, i.e., SL-(2 --> 3). The other SL from human milk is N-acetylneuraminyl-(2 --> 6)-[beta]-D-galactopyranosyl-(1 --> 4)-D-glucose, i.e., SL-(2 --> 6).We now wish to report the enzymatic synthesis of sialyl-lactose by a particulate preparation from rat mammary gland. Chromatographic and periodate oxidation data indicate that the product is SL-(2 --> 3). In addition, preliminary evidence shows that this preparation catalyzes the synthesis of other trisaccharides, such as sialyl-galactosyl-acetylglucosamine. .