aldoheksoosi

Aaldoheksoosi, or aldohexose, is a monosaccharide with six carbon atoms and an aldehyde group at carbon 1. Its general formula is C6H12O6. It belongs to the aldose class of monosaccharides and can exist in multiple stereochemical forms depending on configurations at the C2–C5 positions.

There are 16 possible aldohexoses, arising from the four chiral centers (C2–C5). Each can exist in D- or L- forms, and naturally occurring forms are predominantly D-aldose isomers. The best known aldohexoses are D-glucose, D-galactose, and D-mannose.

In solution, aldohexoses are present in equilibrium between linear and cyclic forms. The most common cyclic forms are six-membered rings called pyranoses, though five-membered furanose forms are possible for some isomers. In aqueous solution, these rings can adopt alpha or beta anomeric configurations at the anomeric carbon, a phenomenon known as mutarotation.

Biological role and occurrence: Aldohexoses are key energy sources in respiration and metabolism, especially glucose, which feeds glycolysis and energy production in nearly all organisms. They are also building blocks for more complex carbohydrates, such as starch and glycogen (glucose polymers), and they are components of glycoproteins and glycolipids. Aldohexoses occur widely in nature, particularly in fruits, honey, and plant saps. They are produced biologically via photosynthesis in plants and commercially by hydrolysis of starch.