[figure: see text] Reactivity of bovine beta 1,4-galactosyltransferase was examined for a series of acyclic acceptor substrates both in the presence and the absence of alpha-lactalbumin (alpha-La). It was found that this enzyme could utilize (R)-3-acetamido-1,2-propanediol (1) as an acceptor substrate regardless of the cofactor protein. The product was determined to be 1-O-beta-D-galactopyranosyl-(R)-3-acetamido-1,2-propanediol (2). Glycerol without the acetamido group was inactive, indicating that this functional group plays a key role in the enzyme reaction.