Homologies in the structures of bull seminal plasma acrosin inhibitors and comparison with other homologous proteinase inhibitors of the Kazal type.

After determination of the amino-acid sequence of a further acrosin inhibitor isolated from bull seminal plasma, the primary structures of the three seminal inhibitors known so far were compared with other homologous structures of protein-protein inhibitors. From the matrix of minimal base changes, a high divergence in the evolution of the seminal inhibitors can be seen. Inhibitors from bull seminal plasma show even a higher degree of relationship to dog submandibular gland inhibitor domain II and the 3rd domain of quail ovomucoid than to acrosin inhibitor from boar seminal plasma.