6deoxyhexose

6-deoxyhexose is a hexose monosaccharide in which the hydroxyl group at carbon-6 is absent, meaning the terminal CH2OH group is replaced by hydrogen. This class includes sugars such as fucose and rhamnose, which occur in various biological polysaccharides and glycoconjugates. Fucose is commonly found in mammalian glycans and glycoproteins, often in the L-configuration, and is a component of many blood group antigens. Rhamnose is widespread in plant and bacterial polysaccharides and is typically found in the L-form.

In biology, 6-deoxyhexoses contribute to cell surface structures and recognition processes. They appear in glycoproteins, glycolipids, and especially bacterial lipopolysaccharides and capsules, where they can influence antigenicity, adhesion, and immune interactions. The presence and pattern of 6-deoxyhexoses in glycans can affect host–pathogen interactions and tissue organization.

Biosynthesis of 6-deoxyhexoses commonly proceeds from activated hexose donors via deoxygenation at C-6. A well-characterized route involves GDP-mannose being converted to GDP-fucose through a dehydration step to form GDP-4-keto-6-deoxymannose, followed by reduction. Similar enzymatic strategies generate other 6-deoxyhexoses on different substrates, underscoring the diversity of deoxy sugars in nature.

Chemically, these sugars can adopt the typical hexose ring forms (pyranose and, less commonly, furanose) and may bear various modifications in glycoconjugates. Their structural diversity supports a range of biological roles and materials in nature.