Dear Mantha,

Y

ou may check Table 1 (list of enzymes) in the publication contained in the following link:

http://onlinelibrary.wiley.com/doi/10.1080/15216540214923/pdf

IUBMB Life, 54: 177–186, 2002

1521-6543/02 $12.00 + .00

DOI: 10.1080/15216540290114450

Review Article

Biosynthesis of Chondroitin/Dermatan Sulfate

Jeremiah E. Silbert1,2 and Geetha Sugumaran1,2,3

1Department of Veterans Affairs Medical Center, Bedford, Massachusetts 01730, USA

2Department of Medicine, Harvard Medical School, Boston, Massachusetts 02115, USA

3Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA

Summary

Chondroitin sulfate and dermatan sulfate are synthesized as galactosaminoglycan polymers containing N-acetylgalactosmine alternating with glucuronic acid. The sugar residues are sulfated to varying degrees and positions depending upon the tissue sources and varying conditions of formation. Epimerization of any of the

glucuronic acid residues to iduronic acid at the polymer level constitutes the formation of dermatan sulfate. Chondroitin/dermatan glycosaminoglycans are covalently attached by a common tetrasaccharide sequence to the serine residues of core proteins while they are adherent to the inner surface of endoplasmic reticulum/Golgi vesicles. Addition of the first sugar residue, xylose, to core proteins

begins in the endoplasmic reticulum, followed by the addition of two galactose residues by two distinct glycosyl transferases in the early cis/medial regions of the Golgi. The linkage tetrasaccharide is completed in the medial/trans Golgi by the addition of the first glucuronic acid residue, followed by transfer of N-acetylgalactosamine to initiate the formation of a galactosaminoglycan rather than a glucosaminoglycan. This specific N-acetylgalactosaminyl transferase

is different from the chondroitin synthase involved in generation of the repeating disaccharide units to form the chondroitin polymer. Sulfation of the chondroitin polymer by specific sulfotransferases occurs as the polymer is being formed. All the enzymes in the pathway for synthesis have been cloned, with the exception of

the glucuronyl to iduronyl epimerase involved in the formation of dermatan residues.

IUBMB Life, 54: 177–186, 2002

Hoping this will be helpful,

Rafik