Negative Impact of Adjacent Coordination on Direct Electrochemistry and Enzymatic Catalysis of Laccase Immobilization onto Multi-wall Carbon Nanotubes Functionalized by Perylene Derivative

Abstract

Influence of interactions between Laccase and carbon nano-tubes modified by perylene derivative on structural parameters and electrochemical behaviors of immobilized redox protein, was investigated systematically by the means of spectrometry, photography and electro-chemistry. Sophisticated interactions including abutting coordination could result in anomalistic agglomeration of nano-composite with Lac incorporation which displayed better hydrophobicity than free Laccase and high resistance of charge shuttle. It would retard the progress of thermal decomposition of nano-composite and would lead to the formation of composite without emission of fluorescence. Strong binding of Laccase with perylenyl derivative (binding constant: 7.5×104 L/mol) would alter the mechanism of electron transferring. T1 Cu2+ of Laccase in the status of complexation played the intra-molecular electron relay with mid-wave potential at −135.6 mV and demonstrated undesirable dynamics in electron transferring (7.7×10−2 s−1). The catalytic function in oxygen reduction was prohibited for the abutting coordination and only weak catalytic effect could be achieved in the presence of electron relay. The whole catalytic cycle was limited by the mass transferring of electron mediator.