Proteolytic cleavage of human fibrinogen by cathepsin B.

: Human fibrinogen was cleaved by human liver cathepsin B in vitro. The time course of the degradation was followed by SDS-PAGE. Using activated cathepsin B in a weight ratio of enzyme to fibrinogen of 1:100 a pH optimum of 6.0 was found at 37 degrees C. For the separation of the fibrinogen degradation products a reversed phase HPLC system was used. Fibrinogen was cleaved by cathepsin B at the C-terminal side of the A alpha-chain, partially also on its N-terminal side and at the N-terminal end of the B beta-chain.