Abstract: Aim: Surface plasmon resonance (SPR) was used to investigate the impact of specific egg yolk immunoglobulin (IgY) on the interaction between tyrosinase and its substrate L-dopa. Methods: Bare gold chip was modified by self-assembly. 3-Mercaptopropionic acid (MPA) was used as the basement membrane to immobilize tyrosinase, and the SPR response signals of tyrosinse binding to specific IgY and L-dopa were monitored in real time. The CLAMP software was used to fit the experimental data to determine the kinetic constants. Results: The affinity constant of tyrosinase to specific IgY (4.50 × 106 L/mol) was higher than that to L-dopa (4.95 × 103 L/mol), and after binding to specific IgY, the binding constant between tyrosinase and L-dopa was decreased significantly. Conclusion: Compared with the substrate L-dopa, tyrosinase was more likely to specifically bind to IgY, and the specific IgY could significantly inhibit the binding of tyrosinase to its substrate and consequently inhibited the enzyme activity on the basis of binding kinetics.

Key words: surface plasmon resonance (SPR), tyrosinase, specific IgY, L-dopa, kinetic constants