The transfer of platelet factor 4 from its proteoglycan carrier to natural and synthetic polymers

1. Transfer of dansyl-platelet factor 4 complexed with a series of glycosaminoglycans to heparin has been detected and studied by measuring changes in the anisotropy of the dansyl fluorescence. The protein was most easily transferred from chondroitin sulphate and least easily from heparan sulphate. 2. The transfer of the dye-labelled protein from its biological chondroitin 4-sulphate proteoglycan carrier to natural and synthetic anionic polymers was similarily followed. The transfer to heparin and dermatan sulphate was shown to be the same whether 3 mM Ca2+ or 8 mM EGTA was present in the solution. 3. The shapes of the binding curves of the dansyl-factor to the polymers have been compared at I = 0.4M. 4. The observed changes in anisotropy of dye fluorescence have been correlated with the charge density and the stereochemistry of the charged groups of the natural polymers. Large complexes are observed with polymers of high negative charge/weight ratios. Less charged polymers containing disaccharide units of iduronic acid and glucosamine N-sulphate will also from large complexes at I = 0.15 M. 5. It is demonstrated that the release of a platelet factor 4 proteoglycan complex in vivo would result in the transfer of the protein to heparin, moderate quantities of either dermatan or heparan sulphates would not prevent this transfer.