Bovine α2-antiplasmin (α2AP) has been purified and partially characterized. The amino acid composition is very similar to that of human α2AP, and the N-terminal (23 residues determined) and reactive site loop sequences (42 residues determined) are highly homologous to those of the human protein. Compared with human α2AP, bovine α2AP has an 18-residue N-terminal extension, homologous with part of the pre-sequence of human α2AP. A re-investigation of the N-terminal sequence of freshly prepared human α2AP reveals a new form extended by 12 residues.
