[Two classes of lysine-binding sites of plasminogen molecule].

Affinity of plasminogen fragments K1, K2-3, K4 and K5 for 6-aminophenyl-Sepharose was investigated to characterize the lysine-binding sites of the protein. K1 and K5 fragments were bound to the affinity column, whereas kringle 2-3 and kringle 4 were not. The results obtained and data known from literature have indicate that two types of lysine-binding sites are present in the plasminogen molecule. Both positively and negatively charged groups of the ligand are necessary for binding with the first-type sites (K4 and K2-3). The interaction between ligands and the second-type sites localized in kringles 1 and 5 is provided by their positively charged group only.