Galactose

**Galactose Etymology and Structure**:
– Coined by Charles Weissman in the mid-19th century
– Derived from Greek word meaning ‘of milk’ and the generic chemical suffix for sugars
– Comparable etymology to the word ‘lactose’
– Galactose exists in open-chain and cyclic forms
– Four cyclic isomers: two pyranose and two furanose
– Galactofuranose found in bacteria, fungi, and protozoa
– Cyclic forms have alpha and beta anomers
– IR and Proton NMR spectra characteristics of galactose

**Galactose Relationship to Lactose**:
– Lactose is a disaccharide of galactose plus glucose
– Galactose combines with glucose to form lactose
– Hydrolysis of lactose catalyzed by lactase and β-galactosidase
– Galactose metabolism via the Leloir pathway
– Galactose required in a 1 to 1 ratio with glucose for lactose synthesis in human lactation
– Synthesis of galactose supplemented by plasma galactose in lactose production

**Galactose Metabolism**:
– Main pathway of galactose metabolism is the Leloir pathway
– Humans have alternate pathways like the De Ley Doudoroff Pathway
– Leloir pathway enzymes: GALM, GALK, GALT, GALE
– Human body cannot directly convert galactose into energy
– Galactosemia results from mutations in Leloir pathway enzymes

**Galactose Sources and History**:
– Found in dairy products, avocados, sugar beets, and other sources
– Synthesized by the body for glycolipids and glycoproteins
– By-product of third-generation ethanol production
– Galactose is present in several tissues
– E. O. Erdmann noted hydrolysis of lactose in 1855
– Louis Pasteur isolated galactose in 1856
– Berthelot renamed it galactose in 1860
– Emil Fischer and Robert Morrell determined galactose’s configuration in 1894

**Galactose in Science and Research**:
– Galactofuranose biosynthesis is studied in Escherichia coli
– Galactose metabolism is linked to ovarian cancer risk
– Galactose therapy shows promise in nephrotic syndrome treatment
– Studies on galactose’s impact on memory and neurodegeneration
– Galactose’s role in milk lactose synthesis is researched

Galactose (Wikipedia)

For the EP by The Sweet Science, see Galactose (EP).

Galactose (/ɡəˈlæktoʊs/, galacto- + -ose, "milk sugar"), sometimes abbreviated Gal, is a monosaccharide sugar that is about as sweet as glucose, and about 65% as sweet as sucrose. It is an aldohexose and a C-4 epimer of glucose. A galactose molecule linked with a glucose molecule forms a lactose molecule.

d-Galactose

Haworth projection of β-d-galactopyranose Fischer projection of d-galactose
Names
IUPAC name Galactose
Systematic IUPAC name (2S,3R,4S,5R,6R)-6-(hydroxymethyl)oxane-2,3,4,5-tetrol
Other names Brain sugar
Identifiers
CAS Number	59-23-4 N
3D model (JSmol)	Interactive image
Beilstein Reference	1724619
ChEBI	CHEBI:28061 Y
ChEMBL	ChEMBL300520 N
ChemSpider	388480 Y
IUPHAR/BPS	4646
KEGG	D04291 N
MeSH	Galactose
PubChem CID	439357
UNII	X2RN3Q8DNE Y
InChI InChI=1S/C6H12O6/c7-1-2-3(8)4(9)5(10)6(11)12-2/h2-11H,1H2/t2−,3+,4+,5−,6+/m1/s1 Y Key: WQZGKKKJIJFFOK-PHYPRBDBSA-N Y InChI=1/C6H12O6/c7-1-2-3(8)4(9)5(10)6(11)12-2/h2-11H,1H2/t2−,3+,4+,5−,6+/m1/s1 Key: WQZGKKKJIJFFOK-PHYPRBDBBU
SMILES O[C@H]1[C@@H](O)[C@H](O[C@H](O)[C@@H]1O)CO
Properties
Chemical formula	C6H12O6
Molar mass	180.156 g·mol−1
Appearance	White solid
Odor	Odorless
Density	1.5 g/cm3
Melting point	168–170 °C (334–338 °F; 441–443 K)
Solubility in water	650 g/L (20 °C)
Magnetic susceptibility (χ)	-103.00·10−6 cm3/mol
Pharmacology
ATC code	V04CE01 (WHO) V08DA02 (WHO) (microparticles)
Hazards
NFPA 704 (fire diamond)	1 0 0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Galactan is a polymeric form of galactose found in hemicellulose, and forming the core of the galactans, a class of natural polymeric carbohydrates.

D-Galactose is also known as brain sugar since it is a component of glycoproteins (oligosaccharide-protein compounds) found in nerve tissue.