The hydrolysis of chemically modified proteins by Factor Xa and thrombin

Bovine thrombin and Factor Xa were shown to hydrolyse slowly several chemically modified proteins. Both enzymes hydrolyse the proteins at trypsin-susceptible bonds, with arginine, lysine or the synthetically generated S-(beta-aminoethyl)cysteine at the P1 position. Both enzymes, however, cleave at far fewer sites than trypsin. The presence of highly polar groups in the P2 position appears to hinder hydrolysis by Factor Xa or thrombin. The presence of hydrophobic or neutral amino acids around this site may make the site more susceptible to hydrolysis. Differences in the hydrolysis patterns between thrombin and Factor Xa are observed.