-Galacturonic acid is a sugar acid, an oxidized form of
-galactose. It is the main component of
pectin
Pectin ( grc, πηκτικός ': "congealed" and "curdled") is a heteropolysaccharide, a structural acid contained in the primary lamella, in the middle lamella, and in the cell walls of terrestrial plants. The principal, chemical component of ...
, in which it exists as the polymer
polygalacturonic acid
Pectic acid, also known as polygalacturonic acid, is a water-insoluble, transparent gelatinous acid existing in over-ripe fruit and some vegetables. It is a product of pectin degradation in plants, and is produced via the interaction between pecti ...
.
[Debra Mohnen "Pectin structure and biosynthesis" Current Opinion in Plant Biology 2008, 11:266–277.
.] In its open form, it has an
aldehyde
In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl grou ...
group at C1 and a
carboxylic acid
In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic ...
group at C6. Other oxidized forms of -galactose are -galactonic acid (carboxylic group at C1) and ''meso''-galactaric acid (
mucic acid
Mucic acid, C6H10O8 or HOOC-(CHOH)4-COOH (also known as galactaric or meso-galactaric acid) is an aldaric acid obtained by nitric acid oxidation of galactose or galactose-containing compounds such as lactose, dulcite, quercite, and most varietie ...
) (carboxylic groups at C1 and C6). It is also a
uronic acid
300px, The Fischer projections of glucose and glucuronic acid">glucose.html" ;"title="Fischer projections of glucose">Fischer projections of glucose and glucuronic acid. Glucose's terminal carbon's primary alcohol group has been oxidized to a ...
or hexuronic acid. Naturally occurring uronic acids are -
glucuronic acid
Glucuronic acid (from Greek γλεῦκος "''wine, must''" and οὖρον "''urine''") is a uronic acid that was first isolated from urine (hence the name). It is found in many gums such as gum arabic (c. 18%), xanthan, and kombucha tea and ...
, -galacturonic acid, -
iduronic acid
-Iduronic acid (IUPAC abbr.: IdoA) is the major uronic acid component of the glycosaminoglycans (GAGs) dermatan sulfate, and heparin. It is also present in heparan sulfate, although here in a minor amount relative to its carbon-5 epimer glucuronic ...
and -
mannuronic acid
Mannuronic acid is a uronic acid monosaccharide that can be derived from mannose. Along with -guluronic acid, -mannuronic acid is a component of alginic acid, a polysaccharide found predominantly in brown algae
Brown algae (singular: alga), com ...
.
References
{{DEFAULTSORT:Galacturonic acid, D-
Uronic acids