hexoser

Hexoser is a nonstandard term that may refer to hexoses, sugars with six carbon atoms. In modern biochemistry the preferred term is hexose (plural hexoses); hexoser can appear in older literature or in some linguistic contexts. When used, the concept encompasses all aldohexoses and ketohexoses with the empirical formula C6H12O6.

Hexoses are divided into aldohexoses and ketohexoses. Aldohexoses include glucose, galactose, and mannose, while rare aldohexoses such as idose, talose, gulose, and allose exist as stereoisomers. The ketohexose most common in biology is fructose. These sugars are chiral, giving rise to multiple stereoisomers; D- and L- forms occur, with D- forms predominating in biological systems.

In aqueous solution, hexoses interconvert between open-chain and cyclic forms. The cyclic forms are primarily pyranose (six-membered rings) and, less commonly, furanose (five-membered rings). In biology, D-glucose and related hexoses are typically discussed in their cyclic forms, which influence their reactivity and metabolism.

Biological roles and metabolism are central to hexoses. They provide a primary energy source through glycolysis and cellular respiration. Glucose, in particular, is taken up by cells via specific transporters and phosphorylated to glucose-6-phosphate to enter metabolic pathways. Hexoses also serve as building blocks for polysaccharides such as glycogen and starch.

Occurrence and applications extend to nature and industry. Hexoses occur in fruits, honey, and many foods; fructose is common in sweeteners. They are used as standards in biochemical assays and, more broadly, as dietary carbohydrates. The term hexoser is rarely used today, with hexose remaining the standard terminology.