Separation of lysozyme-ovotransferrin complexes and the cooperative role of their components in egg white

Abstract

A complex of ovotransferrin and lysozyme was directly isolated from egg white using an anti-transferrin antibody-immobilized membrane after antiserum proteins were separated by non-denaturing two-dimensional electrophoresis and transferred onto a membrane. The complex retained lysozyme activity that catalyzes the breakdown of peptidoglycans in the bacterial cell wall at the β1–4 bond between N-acetylmuramic acid and N-acetylglucosamine residues. The activity of the purified lysozyme was suppressed to 6.4% in the presence of 1 µmol Fe²⁺, whereas that of the mixture of the purified lysozyme and ovotransferrin was maintained at 58%. The activity of the purified lysozyme was suppressed to 35% in the presence of 10 nmol Fe³⁺, whereas that of the mixture of the purified lysozyme and ovotransferrin was maintained at 66%. Furthermore, the bacteriolytic activity of egg white with reduced glycoproteins such as ovotransferrin was assessed, and the bacteriolytic activity was found to be suppressed in the presence of Fe²⁺ and Fe³⁺. This suppression was ions, thereby alleviating the inhibition of lysozyme activity by iron ions. A complex of ovotransferrin and lysozyme is efficient because ovotransferrin effectively capture iron ions near lysozyme. Thus, protein complexes containing enzymes can be applied to control their activity.