[Properties of duck ovomucoid purified by affinity chromatography on trypsin-Sepharose]

Ovomucoid, a proteinase inhibitor from duck egg protein, was purified by affinity chromatography on trypsin-Sepharose. Isoelectric focusing revealed that the purified protein is represented by one major component with a pI of 3,8. The molecular weight of the inhibitor as determined by the sedimentation equilibrium method is 22 000 plus or minus 1000. One molecule of duck ovomucoid can bind two molecules of trypsin and one molecule of chymotrypsin. Modification of the protein by maleic anhydride showed that both centers responsible for trypsin binding contain lysine residues.