STUDIES ON BINDING OF GLYCOSAMINOGLYCANS TO STREPTOCOCCUS-PYOGENES BYUSING I-125 HEPARAN-SULFATE AS A PROBE

Binding of I-125-heparan sulphate to the cell surface of Streptococcus pyogenes is mediated by proteins, that could be released from the str eptococcal cell wall by using alkaline buffer. SDS-electrophoresis rev ealed two bands with molecular weights of 63 and 58 kDa. Binding of th e I-125-labelled heparan sulphate probe to streptococci seems to be du e to charge interactions, as the same probe was displaced by unlabelle d heparan sulphate, other negatively charged molecules such as heparin , dextran sulphate, dermatan sulphate or by high ionic strength. The i nteraction was also strongly influenced by pH. The binding constant at pH 7.2 was estimated to be 9.8 x 10(6) mol/l, suggesting a moderate a ffinity. The presence of collagen of different types enhanced binding of I-125-labelled heparan sulphate to streptococci, whereas fibronecti n and vitronectin had an inhibitory effect. The cooperation between he paran sulphate and collagen could be important for the adhesion of str eptococci to connective tissue.