a-D-半乳糖醛酸,D-(+)-Galacturonic acid

Pectin is any mixture of complex, colloidal, macromolecular plant galacturonans containing a large proportion of D-galactopyranosyluronic acid residues in alpha-(1->4) linkage, the carboxy groups of which may be esterified to varying degrees by methyl groups or be partially or completely converted into salts. The structure shown is that of the parent polygalacturonan. It has a role as an antidiarrhoeal drug, a food stabiliser, a food emulsifier, a food thickening agent, a food gelling agent, a plant metabolite and a Saccharomyces cerevisiae metabolite. It is a conjugate acid of a pectate.

Pectic acid, also known as pectate or D-galacturonan, belongs to the class of organic compounds known as glucuronic acid derivatives. Glucuronic acid derivatives are compounds containing a glucuronic acid moiety (or a derivative), which consists of a glucose moiety with the C6 carbon oxidized to a carboxylic acid. Pectic acid is soluble (in water) and a weakly acidic compound (based on its pKa). Within the cell, pectic acid is primarily located in the cytoplasm. Pectic acid is also a parent compound for other transformation products, including but not limited to, 1-phospho-alpha-D-galacturonic acid, UDP-alpha-D-galacturonic acid, and UDP-D-galacturonic acid.

The α-anomer of D-galacturonic acid.