Glycolaldehyde

Glycolaldehyde

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Encyclopedia
Glycolaldehyde is the smallest possible molecule that contains both an aldehyde
Aldehyde
An aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....

 group and a hydroxyl group
Hydroxyl
A hydroxyl is a chemical group containing an oxygen atom covalently bonded with a hydrogen atom. In inorganic chemistry, the hydroxyl group is known as the hydroxide ion, and scientists and reference works generally use these different terms though they refer to the same chemical structure in...

. It is the only possible diose
Diose
A diose is a monosaccharide containing two carbon atoms. Because the general chemical formula of an unmodified monosaccharide is n, where n is three or greater, it does not meet the formal definition of a monosaccharide. However, since it does fit the formula n, it is sometimes thought of as the...

, a 2-carbon monosaccharide
Monosaccharide
Monosaccharides are the most basic units of biologically important carbohydrates. They are the simplest form of sugar and are usually colorless, water-soluble, crystalline solids. Some monosaccharides have a sweet taste. Examples of monosaccharides include glucose , fructose , galactose, xylose...

, although a diose is not strictly a saccharide. It is the simplest possible sugar.

Formation


Glycolaldehyde is an intermediate in the formose reaction
Formose reaction
The formose reaction, discovered by Aleksandr Butlerov in 1861, involves the formation of sugars from formaldehyde. Formose is a contraction of formaldehyde and aldose.-Reaction and mechanism:...

.

Glycolaldehyde forms from many precursors, including the amino acid
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...

 glycine
Glycine
Glycine is an organic compound with the formula NH2CH2COOH. Having a hydrogen substituent as its 'side chain', glycine is the smallest of the 20 amino acids commonly found in proteins. Its codons are GGU, GGC, GGA, GGG cf. the genetic code.Glycine is a colourless, sweet-tasting crystalline solid...

. It can form by action of ketolase on fructose 1,6-bisphosphate
Fructose 1,6-bisphosphate
Fructose 1,6-bisphosphate is fructose sugar phosphorylated on carbons 1 and 6 . The β-D-form of this compound is very common in cells...

 in an alternate glycolysis pathway. This compound is transferred by thiamine pyrophosphate
Thiamine pyrophosphate
Thiamine pyrophosphate , or thiamine diphosphate , is a thiamine derivative which is produced by the enzyme thiamine pyrophosphatase. Thiamine pyrophosphate is a coenzyme that is present in all living systems, in which it catalyzes several biochemical reactions...

 during the pentose phosphate shunt.

In purine catabolism
Purine metabolism
-Biosynthesis:Purines are biologically synthesized as nucleotides and in particular as ribotides, i.e. bases attached to ribose 5-phosphate. A key regulatory step is the production of 5-phospho-α-D-ribosyl 1-pyrophosphate by PRPP synthetase, which is activated by inorganic phosphate and...

, xanthine
Xanthine
Xanthine , is a purine base found in most human body tissues and fluids and in other organisms. A number of stimulants are derived from xanthine, including caffeine and theobromine....

 is first converted to urate
Uric acid
Uric acid is a heterocyclic compound of carbon, nitrogen, oxygen, and hydrogen with the formula C5H4N4O3. It forms ions and salts known as urates and acid urates such as ammonium acid urate. Uric acid is created when the body breaks down purine nucleotides. High blood concentrations of uric acid...

. This is converted to 5-hydroxyisourate, which decarboxylates to allantoin
Allantoin
Allantoin is a chemical compound with formula C4H6N4O3. It is also called 5-ureidohydantoin or glyoxyldiureide. It is a diureide of glyoxylic acid....

 and allantoic acid
Allantoic acid
Allantoic acid is an organic compound with the chemical formula C4H8N4O4. It is a crystalline acid obtained by hydrolysis of allantoin....

. After hydrolyzing one urea
Urea
Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....

, this leaves glycolureate. After hydrolyzing the second urea, glycolaldehyde is left. Two glycolaldehydes condense to form erythrose
Erythrose
Erythrose is a tetrose carbohydrate with chemical formula C4H8O4. It has one aldehyde group and so is part of the aldose family. The natural isomer is D-erythrose....

 4-phosphate, which goes to the pentose phosphate shunt again.

In the media


Glycolaldehyde was identified in a giant cloud of gas and dust near the center of our own Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...

Galaxy and recently also in a star-forming region.