LAUSR

Interaction of Ni complex (Salen = N,N´-ethylene bis (salicylideneimine)) with hen egg white lysozyme (HEWL) was studied by absorption spectroscopy, competitive binding study and thermal denaturation study. The protein binding affinity of Ni complex was found to be (3.0 × 10 3 M -1 ). The binding plot obtained from the absorption titration data gives a binding constant of 2.4 (± 0.3) × 10 3 M -1 . It was found that the charge transfer band of the metal complex was perturbed in the presence of HEWL. Thermal denaturation study of HEWL with Ni complex revealed the ΔTm value of 5 ± 0.2 °C. The thermodynamic parameters (ΔHo > 0 and ΔSo > 0) showed that the hydrophobic interaction leads to the increasing entropy brought about by interaction with the complex. The negative ΔGo values for the interaction of HEWL with the Ni complex indicate the spontaneity of the interaction.