Description
Factor Xa cleaves after the arginine residue in its preferred cleavage site Ile-(Glu or Asp)-Gly-Arg. It will sometimes cleave at other basic residues, depending on the conformation of the protein substrate (1,2,3). The most common secondary site, among those that have been sequenced, is Gly-Arg. There seems to be a correlation between proteins that are unstable in E.coli and those that are cleaved by Factor Xa at secondary sites; this may indicate that these proteins are in a partially unfolded state (Walker, I., Riggs, P., unpublished observations). Factor Xa will not cleave a site followed by proline or arginine.