Interaction of small molecules with fungal laccase: A Surface Plasmon Resonance based study

• Screening of binding affinity of small molecules towards T. versicolor laccase enzyme using Surface Plasmon Resonance (SPR).
• Evaluation of binding kinetics for laccase enzyme.
• SPR study confirmed by spectrophotometric assay method.
• IC50 values were calculated by using % inhibition of laccase enzyme.

Laccases have a great potential for use in industrial and biotechnological applications. It has affinity towards phenolics and finds major applications in the field of bioremediation. Here, Surface Plasmon Resonance (SPR) as a biosensor with immobilized laccase on chip surface has been studied. Laccase was immobilized by thiol coupling method and compounds containing increasing number of hydroxyl groups were analyzed for their binding affinity at various concentrations in millimolar range. The small molecules like phloroglucinol (1.532 × 10−8 M), crocin (3.204 × 10−3 M), ascorbic acid (8.331 × 10−8 M), kojic acid (6.411 × 10−7 M) and saffron (3.466 × 10−7 M) were studied and respective KD values are obtained. The results were also confirmed by inhibition assay and IC50 values were calculated. All these molecules showed different affinity towards laccase in terms of KD values. This method may be useful for preliminary screening and characterization of small molecules as laccase substrates, inhibitors or modulators of activity. This method will be useful for rapid screening of phenolics in waste water because of high sensitivity.