Evidence that the conformation of unliganded human plasminogen is maintained via an intramolecular interaction between the lysine-binding site of kringle 5 and the N-terminal peptide

摘要: Human Glu-plasminogen adopts at least three conformations that provide a means for regulating the specificity of its activation in vivo. It has been proposed previously closed (alpha) conformation human is maintained through physical interaction kringle 5 domain and lysine residue within N-terminal peptide (NTP). To examine this hypothesis, site-directed mutagenesis was used to generate variant proteins containing substitutions either aspartic acid residues anionic centre or conserved NTP. Size-exclusion HPLC rates plasminogen by urokinase-type activator were determine conformational states these variants. Variants with lysine-binding site demonstrated extended conformations, as did variants alanine Lys50 Lys62. In contrast, molecules which NTP Lys20 Lys33 replaced shown adopt conformations. We conclude involved maintaining via an NTP, probably and/or These conclusions advance current model initial stages fibrinolysis during fibrin thought compete site.