The targeting of autologous vaccines toward antigen presenting cells (APCs) via the in vivo complexation between anti α-Gal (anti-Gal) antibodies and α-Gal antigens presents a promising cancer immunotherapy with enhanced immunogenicity. This strategy takes advantage of the ubiquitous anti-Gal antibody in human serum. In contrast to the α-Gal epitope, the recent identification of high titers of anti-l-rhamnose (anti-Rha) antibodies in humans reveals a new approach toward immunotherapy employing l-rhamnose (Rha) monosaccharides. In order to evaluate this simple antigen in preclinical applications, we have synthesized Rha-conjugated immunogens and successfully induced high titers of anti-Rha antibodies in wildtype mice. Moreover, our studies demonstrate for the first time that wildtype mice could replace α1,3galactosyltransferase knockout (α1,3GT KO) mice in such antigen/antibody-mediated vaccine design when developing cancer immunotherapies.

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Poly(ethylene glycol) (PEG) conjugation (i.e. PEGylation) is a commonly used strategy to increase the circulatory half-life of therapeutic proteins and colloids, however, few viable alternatives exist to replicate its functions. Herein, we report a method for the rapid site-selective glycosylation of proteins with various sized carbohydrates, up to a molecular weight (MW) of 10,000 Da, thus, serving as a potential alternative for PEGylation. More importantly, the method developed has two unique features. First, traditional protecting group strategies that typically accompany the modification of the carbohydrate fragments are circumvented, allowing for the facile site-selective glycosylation of a desired protein with various sized glycans. Second, the methodology employed is not limited by oligosaccharide size; consequently, glycans of a similar MW to that of PEG, used in the PEGylation of therapeutic proteins, can be employed. To demonstrate the usefulness of this technology, hemoglobin (Hb) was site-selectively glycosylated with a series of carbohydrates of increasing MW (504 to ~10,000 Da). Hb was selected based on the vast wealth of biochemical and biophysical knowledge present in the literature and because of its use as a precursor in the synthesis/formulation of artificial red blood cell substitutes. Following the successful site-selective glycosylation of Hb, the impact of increasing the glycan MW on Hb’s biophysical properties was investigated in vitro.

Escherichia coli O127:K63(B8) possesses high human blood group H (O) activity due to its O-antigen repeating unit structure. In this work, the wbiQ gene from E. coli O127:K63(B8) was expressed in E. coli BL21 (DE3) and purified as a fusion protein containing an N-terminal GST affinity tag. Using the GST-WbiQ fusion protein, the wbiQ gene was identified to encode an α1,2-fucosyltransferase using a radioactivity based assay, thin layer chromatography assay, as well confirming product formation by using mass spectrometry and NMR spectroscopy. The fused enzyme (GST-WbiQ) has an optimal pH range from pH 6.5 to pH 7.5 and does not require the presence of a divalent metal to be enzymatically active. WbiQ displays strict substrate specificity, displaying activity only towards acceptors that contain Gal-β1,3-GalNAc-α-OR linkages; indicating that both the Gal and GalNAc residues are vital for enzymatic activity. In addition, WbiQ was used to prepare the H-type 3 blood group antigen, Fuc-α1,2-Gal-β1,3-GalNAc-α-OMe, on a milligram scale.

Synthesis of Rare Sugars with L-Fuculose-1-phosphate Aldolase (FucA) from Thermus thermophilus HB8. -A one-pot, four-enzyme approach yields the rare sugars (D)-psicose (III), (D)-sorbose (IV), (L)-tagatose, and (L)-fructose in the presence of the thermophilic source-derived title aldolase as the catalyst. The use of this bio-agent is more efficient than its E.coli counterpart. Importantly, this approach does not require the donor substrate dihydroxyacetone phosphate, a rather expensive and unstable compound, and most significantly, the inexpensive racemic glycerol phosphate(I) greatly reduces the synthetic cost. -(LI, Z.; CAI, L.; QI, Q.; STYSLINGER, T. J.; ZHAO, G.; WANG*, P. G.; Bioorg. Med. Chem. Lett. 21 (2011) 17, 5084-5087, http://dx.