Van Dorst J A, Tikkanen J M, Krezdorn C H, Streiff M B, Berger E G, Van Kuik J A, Kamerling J P, Vliegenthart J F
Bijvoet Center, Department of Bio-Organic Chemistry, Utrecht University, The Netherlands.
Eur J Biochem. 1996 Dec 15;242(3):674-81. doi: 10.1111/j.1432-1033.1996.0674r.x.
The acceptor specificities of rat liver Gal(beta 1-4)GlcNAc alpha-2,6-sialyltransferase, recombinant full-length human liver Gal(beta 1-4)GlcNAc alpha-2,6-sialyltransferase, and a soluble form of recombinant rat liver Gal(beta 1-3/4)GlcNAc alpha-2,3-sialyltransferase were studied with a panel of analogues of the trisaccharide Gal(beta 1-4)GlcNAc(beta 1-2)Man(alpha 1-O)(CH2)7CH3. These analogues contain structural variants of D-galactose, modified at either C3, C4 or C5 by deoxygenation, fluorination, O-methylation, epimerization, or by the introduction of an amino group. In addition, the enantiomer of D-galactose is included. The alpha-2,6-sialyltransferases tolerated most of the modifications at the galactose residue to some extent, whereas the alpha-2,3-sialyltransferase displayed a narrower specificity. Molecular dynamics simulations were performed in order to correlate enzymatic activity to three-dimensional structure. Ineffective acceptors for rat liver alpha-2,6-sialyltransferase were shown to be inhibitory towards the enzyme; likewise, the alpha-2,3-sialyltransferase was found to be inhibited by all non-substrates. Modified sialyloligosaccharides were obtained on a milligram scale by incubation of effective acceptors with one of each of the three enzymes, and characterized by 500-MHz 1H-NMR spectroscopy.
