Effect of oversulfated chondroitin-6-sulfate or oversulfated fucoidan in the activation of glutamic plasminogen by tissue plasminogen activator: role of lysine and cyanogen bromide-fibrinogen

Abstract

Fucoidan and chondroitin-6-sulfate were oversulfated using chlorosulfonic acid-pyridine complex and were isolated as the sodium salt. Infrared analysis of oversulfated compounds showed introduction of sulfate groups in new positions, and in-vitro studies of the compounds showed a significant increase in the anticoagulant property. Addition of 28.6 microg/ml oversulfated compound gave a two-fold to four-fold increase in the rate of enhancement of activation of glutamic plasminogen by tissue plasminogen activator using 0.05 mol/l Tris buffer (pH 7.35) containing physiological concentrations of NaCl (0.9%). Under these conditions, unfractionated heparin was not active and the native compounds gave less than 30% enhancement. In the present study, the effect of lysine or cyanogen bromide-treated fibrinogen, alone or in combination with the oversulfated compounds, on the activation of glutamic plasminogen by tissue plasminogen activator was investigated. Addition of 16.2 mmol/l L-lysine gave three-fold to four-fold enhancement of activation, which was further enhanced to five-fold to six-fold by addition of 2.86 microg/ml oversulfated chondroitin-6-sulfate or oversulfated fucoidan. Cyanogen bromide-treated fibrinogen (50 microg/ml) gave a 10-fold enhancement of activation by itself, and addition of 2.86 microg/ml oversulfated compounds amplified this to 15-fold. A 25-fold to 35-fold enhancement of activation of glutamic plasminogen was obtained when 2.86 microg/ml oversulfated compounds were combined with 16.2 mmol/l lysine and 50 microg/ml cyanogen bromide-treated fibrinogen. Dilution studies showed that the amplification of the enhancement of lysine by 2.86 microg/ml oversulfated compound was related to interaction of the cofactors with both glutamic plasminogen and tissue plasminogen activator.