Abstract
The dermatan sulfate (DS) isolated from the ray skin
Raja montagui was identified and characterized. Its average molecular weight (Mw) and sulfate content were 39
kDa and 25% w/w, respectively. This DS prolonged thrombin time and activated partial thromboplastin time and inhibited the thrombin generation in a concentration-dependent manner whereas it had no effect on the anti-Xa assay and on platelet function. Data from the anti-IIa assay allowed the assessment of the specific anticoagulant activity which was 40
units/mg. The kinetics of the thrombin inhibition by heparin cofactor II (HCII) has been studied as a function of DS concentration according to a kinetic model in which the polysaccharide binds quickly to the inhibitor and forms a complex more reactive than the free inhibitor towards thrombin. This DS accelerated thrombin inhibition exclusively by HCII. The dissociation constant of the DS–HCII complex,
K
DSHCII, and the rate constant of the thrombin inhibition by this complex,
k, were (2.93
±
0.25)
×
10
−
6
M and (2.2
±
0.35)
×
10
9M
−
1
min
−
1
, respectively.
Our findings indicated that the major polysaccharide in the skin of the ray
Raja montagui was a DS endowed with a high anticoagulant effect mediated by HCII and which may constitute an anticoagulant drug of interest in anticoagulant therapy.