Cleavage of plasminogen by elastase yields angiostatin (kringles 1-4) or angiostatin-like fragments (kringles 1-3). HTI's angiostatin product is derived from a single cleavage within the plasminogen molecule resulting in a product that includes Kringles 1-4 as well as the NH2-terminal 78 amino acids that are absent in the elastase generated product. (K1-K5 = the 5 kringle domains, B-CHAIN = catalytic domain of plasmin, and the arrows indicate the sites of proteolytic cleavage by plasmin, elastase, HTI's proprietary enzyme, and plasminogen activators (PA'S)). Purity >95% by SDS-PAGE