∆UA – (GalNAc,4S – IdoA)n – GalNAc,4S
where n is number of disaccharide units
n = 1 in a tetrasaccharide (dp4)
n =2 in a hexasaccharide (dp6)
n = 3 in an octasaccharide (dp8) etc…..
Uronic acid (∆UA) at the non-reducing ends of the oligosaccharides has a C4-C5 double bond as a result of endolytic scission.
The main disaccharide in the original dermatan sulfate was IdoA – GalNAc,4S (88%) with minor quantities of 6-sulfated and 2,4 disulfated units (5% and 7% respectively) also present.
Main Dermatan Sulphate Disaccharide Unit