36anhydroLgalactose

3,6-anhydro-L-galactose, abbreviated AHG, is a hexose-derived sugar residue that occurs as a structural component of agarose, the gelling polysaccharide found in red algae. In the repeating disaccharide unit of agarose, AHG is linked to D-galactose in a β(1→4) fashion, forming the pattern [-β-D-Gal-(1→4)-3,6-anhydro-L-Gal-(1→]n. The designation 3,6-anhydro refers to a covalent bridge formed between carbon atoms 3 and 6 on the galactose unit, a structural feature that distinguishes AHG-containing polysaccharides from other galactans.

Occurrence and biosynthesis

AHG is formed and incorporated into agarose during the biosynthesis of agar-containing polysaccharides in red algae. It remains an integral part of mature agarose and related oligosaccharides, contributing to the distinctive physical properties of agarose gels.

Significance and applications

AHG-containing carbohydrates are of interest in carbohydrate chemistry and marine biotechnology. They serve as model substrates for studying agarose-degrading enzymes (agarases) and for exploring the structure-function relationships of agarose in gel formation. AHG-containing oligosaccharides are also used in basic research to understand how sugar modifications influence polysaccharide architecture and interactions with other biomolecules.

Safety and handling

As a naturally occurring carbohydrate constituent, AHG itself is handled in the same general manner as other carbohydrate materials used in laboratory research. No specific hazards are associated with AHG beyond standard laboratory precautions.