Localization of epitopes for monoclonal antibodies to urokinase‐type plasminogen activator

摘要: 1We localized the epitopes for several murine mAbs to human urokinase-type plasminogen activator (uPA) by Ala scanning mutagenesis and related localization effects of on molecular interactions uPA. Several antibodies against serine proteinase domain (SPD) were found have overlapping composed variable combinations Arg178, Arg179, His180, Arg181, Tyr209, Lys211, Asp214 in so-called 37-loop 60-loop, located near active site taking part binding uPA inhibitor-1 (PAI-1). Besides inhibiting uPA-catalysed activation, all SPD strongly delayed PAI-1, decreasing second-order rate constant 15- 6500-fold. There was no correlation between relative 60-loop substitutions antibodies, indicating that did not delay complex formation blocking residues specific importance uPA–PAI-1 reaction, but rather steric hindrance access PAI-1 site. The affinity only slightly lower than free uPA, are exposed complex. two kringle included Arg108, Arg109, Arg110. ability these block polyanions correlated with a reduced uPA–polyanion after substitution three Arg residues.