Binds plasminogen, specifically, and in a concentration and lysine-dependent manner. Plasminogen is the precursor of plasmin, a serine protease that cleaves fibrin, fibronectin, laminin and vitronectin. Acquisition of plasminogen/plasmin could enable H.pylori to degrade host components (By similarity). The plasminogen-binding region is localized on the surface the bacterium. Plasminogen bound to PgbB is capable of being converted to functionally active plasmin.