galattose

Galactose, sometimes referred to as galattose in some languages, is a monosaccharide sugar and an aldose hexose. It exists primarily in the D-configuration in nature and is a structural isomer of glucose, differing in the orientation of the hydroxyl group at carbon 4. It is a component of lactose, the disaccharide found in milk, where β-D-galactose is linked to glucose.

In biological systems, galactose is typically obtained from the digestion of lactose and absorbed from the intestine into the bloodstream. It is not a major dietary source on its own but becomes important as a metabolic substrate. Galactose is metabolized through the Leloir pathway, which involves sequential enzymes: galactokinase converts galactose to galactose-1-phosphate, galactose-1-phosphate uridylyltransferase then converts it to UDP-galactose and glucose-1-phosphate, and UDP-galactose 4-epimerase can convert UDP-galactose to UDP-glucose. UDP-glucose and glucose-1-phosphate feed into glycolysis, glycogen synthesis, and the biosynthesis of glycoproteins and glycolipids.

Galactose plays a role in the structure of cell membranes and in the modification of proteins and lipids. It is also studied for its potential in diagnostic tests and as a precursor in various biochemical syntheses.

Health considerations include galactosemia, a group of inherited disorders caused by defects in the enzymes of the Leloir pathway, most commonly GALT deficiency. Newborns with galactosemia require strict dietary management to avoid serious complications. Galactose intake is typically monitored through avoidance of lactose-containing foods in affected individuals.