Fucose

Fucose is a deoxyhexose monosaccharide, typically the L-enantiomer, with the chemical name 6-deoxy-L-fucose. It is a common component of glycoconjugates in plants, animals, and microorganisms, where it is incorporated into glycoproteins, glycolipids, and proteoglycans as various fucose-containing residues.

In biological systems, fucose is primarily donated to glycans by the activated nucleotide sugar GDP-fucose. The core biosynthesis pathway (de novo) converts GDP-mannose to GDP-fucose, and a salvage pathway can recycle free fucose into GDP-fucose. The GDP-fucose donor is transported into the Golgi apparatus by specific transporters and then transferred to glycan acceptors by fucosyltransferases, generating a range of linkages such as alpha-1,3-, alpha-1,4-, and alpha-1,6-fucosyl bonds. A notable type of modification is core fucosylation, catalyzed by FUT8, which attaches fucose to the innermost N-acetylglucosamine of N-glycans.

Fucosylation affects many biological processes, including cell-cell adhesion, signaling, and immune recognition. It is essential for the formation of blood group antigens (such as H, Lewis, and ABO determinants) and for selectin-mediated leukocyte trafficking through sialyl Lewis X structures. Altered fucosylation patterns are observed in cancer and inflammatory diseases, and fucosylation defects underlie certain congenital disorders of glycosylation.

Analytical methods for fucose include chromatographic and mass spectrometric approaches, as well as enzymatic assays using fucosidases.