alphaglucose

Alpha‑glucose, also known as alpha-D‑glucose, is a monosaccharide belonging to the hexose class. It has the molecular formula C6H12O6 and exists as a pyranose ring in aqueous solution, typically in the α‑anomeric form where the hydroxyl group attached to the anomeric carbon (C1) is on the opposite side of the ring from the ring oxygen. The systematic IUPAC name is (2R,3R,4S,5R)-1,5-dihydroxy-3,4-dimethylhexane‑2,3,4,5,6-pentol.

The α‑anomer differs stereochemically from the β‑anomer by the orientation of the anomeric hydroxyl group; in the β‑anomer it is on the same side as the ring oxygen. In solution, α‑glucose interconverts with β‑glucose through mutarotation, reaching an equilibrium of about 36 % α and 64 % β in water at 25 °C.

Alpha‑glucose is a key component of many natural polymers. In plants it forms the α‑1,4‑glycosidic bonds that constitute starch and glycogen, providing a dense energy reserve that can be mobilised to glucose. It is also incorporated into storage polysaccharides of some bacteria and in the α‑1,6‑glycosidic linkages found in glycogen branching points. The α‑linkages are hydrolysed by sucrase and maltase in the small intestine to release free glucose for absorption.

Beyond its biological roles, α‑glucose is used industrially in the synthesis of vaccines, enzyme substrates, and as a starting material in carbohydrate chemistry. Its solubility, non‑acidic nature, and ability to form crystalline hydrates make it useful in pharmaceutical formulations. Advances in enzymology have also allowed the selective synthesis of α‑glucose derivatives for use as probes in metabolic studies.