The influence of an intramolecular hydrogen bond in differential recognition of inhibitory acceptor analogs by human ABO(H) blood group A and B glycosyltransferases.

Human ABO(H) blood group glycosyltransferases GTA and GTB catalyze the final monosaccharide addition in the biosynthesis of the human A and B blood group antigens. GTA and GTB utilize a common acceptor, the H antigen disaccharide alpha-l-Fucp-(1-->2)-beta-d-Galp-OR, but different donors, where GTA transfers GalNAc from UDP-GalNAc and GTB transfers Gal from UDP-Gal. GTA and GTB are two of the most homologous enzymes known to transfer different donors and differ in only 4 amino acid residues, but one in particular (Leu/Met-266) has been shown to dominate the selection between donor sugars.

A beta-helical antifreeze protein isoform with increased activity. Structural and functional insights.

The insect spruce budworm (Choristoneura fumiferana)(Cf) produces a number of isoforms of its highly active antifreeze protein (CfAFP). Although most of the CfAFP isoforms are in the 9-kDa range, isoforms containing a 30- or 31-amino acid insertion have also been identified. Here we describe the functional and structural analysis of a selected long isoform, CfAFP-501.

Elevated temperature and tyrosine iodination aid in the crystallization and structure determination of an antifreeze protein.

Production and refolding of recombinant Choristoneura fumiferana antifreeze protein (CfAFP) leads to a disulfide-bonded product containing dynamic conformational microheterogeneity. Difficulties in the crystallization of this protein arising from its microheterogeneity were overcome by screening of crystallization conditions at various temperatures and finally using a temperature of 318 K to obtain diffraction-quality crystals. In addition, heavy-atom derivatization of this protein required the iodination of a specific tyrosine residue, leading to the successful single anomalous scattering (SAS) structure determination.

Crystal structure of beta-helical antifreeze protein points to a general ice binding model.

Reported here is the 2.3 A resolution crystal structure of spruce budworm (Choristoneura fumiferana) antifreeze protein (CfAFP), solved by single anomalous scattering. The structure reveals an extremely regular left-handed beta-helical platform consisting of 15-amino acid loops with a repetitive Thr-X-Thr motif displayed on one of the helix's three faces.