α-Gal Lewis A (Galα1-3GlcNAcβ1-3(Fucα1-4)GlcNAc) 

α-Gal Lewis A (Galα1-3GlcNAcβ1-3(Fucα1-4)GlcNAc)  is a branched trisaccharide antigen found in human blood group A structures and mucins, appearing as a white powder used in glycan research for immune studies and pathogen mimicry. Synthesized enzymatically or chemically, it features α-1,3-galactose on a Lewis A core, enabling specific lectin binding and antibody recognition, with applications in diagnostics, vaccines, and allergy research; purity exceeds 95% via HPLC/NMR, stable at -20°C for years. Appearance Pristine white to off-white amorphous or crystalline powder. Melting point ~200-210°C; water solubility >100 g/L. Source Naturally in human A blood group secretions, gastrointestinal mucins, and select pathogens. Commercially via glycosyltransferase cascades on GlcNAc acceptors using E. coli or yeast expression systems. Molecular Weight and Structure Molecular mass 811.73 g/mol, formula C₃₂H₅₅N₃O₂₄. Galα1-3GlcNAcβ1-3(Fucα1-4)GlcNAc branched scaffold with rigid glycosidic linkages. Sugar Specificity Binds anti-α-Gal antibodies, Lewis lectins (e.g., LEA), and helminth adhesins via terminal Galα1-3 and Fucα1-4. Hydrolyzed by α-galactosidases (e.g., from Bacteroides) and α1-4 fucosidases. Biological Activity Elicits IgE/IgG responses in α-Gal syndrome; inhibits norovirus/rotavirus adhesion. Modulates allergy, promotes T-reg cells, targets cancer glycans, and barriers xenotransplants. Purity and Microbial Contamination ≥95-99% by HPLC/NMR; endotoxins <10 EU/mg, no pathogens. Heavy metals per ICH Q3D; moisture <10% post-lyophilization. Identity and Quality Control ¹H-NMR for anomeric protons; LC-MS/MS for [M+H]+; HPAEC-PAD for monosaccharides. COA includes heavy metals (ICP-MS), residuals (GC-MS). Shelf Life and Storage 24-36 months at -20°C under N₂, lyophilized. Ambient short-term if desiccated; avoid humidity to prevent hydrolysis. Applications Blood typing assays, glycan arrays, anti-Gal vaccine development. Xenotransplant research, anti-infective mimics, functional foods. Key Characteristics Gastric-stable; colonic fermentation to SCFAs; epitope mimicry for precise screening. Citation Links https://en.wikipedia.org/wiki/Lewis_A_antigen https://pmc.ncbi.nlm.nih.gov/articles/PMC6344609/ https://www.qa-bio.com/product/alpha1-3-gal-standard/ https://pmc.ncbi.nlm.nih.gov/articles/PMC2271034/ https://pubs.acs.org/doi/10.1021/ja0493205 https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2020.01420/full https://glycosmos.org/ https://pubmed.ncbi.nlm.nih.gov/40591906/ https://academic.oup.com/glycob/article/12/4/241/1592386/cwe123.pdf https://www.sigmaaldrich.com/US/en/search/alpha-gal-lewis-a