iduronate

Iduronate refers to the salt or ester form of iduronic acid, a hexuronic acid that is the C-5 epimer of glucuronic acid. It is a component of several glycosaminoglycans, notably dermatan sulfate, heparan sulfate, and heparin, where iduronate residues contribute to chain conformation and binding properties.

In glycosaminoglycan biosynthesis, glucuronic acid residues can be epimerized to iduronic acid by C5-epimerases, generating iduronate-containing domains. These residues can also be further sulfated at various positions, producing iduronic acid 2-sulfate or 6-sulfate forms that influence interactions with proteins and enzymes.

Biological roles and clinical relevance center on the flexible, sulfated iduronate-rich regions of GAGs, which are important for binding growth factors, chemokines, and anticoagulant activity in heparin. Defects in degradation of iduronate-containing GAGs lead to mucopolysaccharidoses, such as Hurler syndrome (alpha-L-iduronidase deficiency) and Hunter syndrome (iduronate-2-sulfatase deficiency), with accumulation of dermatan sulfate and heparan sulfate in tissues.

In research and clinical contexts, iduronate residues are used to characterize GAG structure and function. Salts such as sodium iduronate may be employed as reagents in biochemical assays and as standards for analytical measurements of uronic acids.