Phycocyanin of marine Oscillatoria sp. inhibits lipoxygenase by protein-protein interaction-induced change of active site entry apace: A model for non-specific biofunctions of phycocyanins.

Abstract An overview of the biological properties of phycocyanin (PC) amply illustrates that it may not have any specific functional feature towards any system at which it may elicit a specific function, but for the molecular interactions. Nevertheless, based on existing evidences, it is hypothesized that PC has more than one functional target with the interacting systems; therefore, it has diversity of effects. The mechanism of PC action remains elusive of a comprehensive idea. The present investigation focuses on the pro inflammatory enzyme, lipoxygenase (LOX) inhibiting property of PC purified from Oscillatoria sp. Enzyme kinetics studies show that the molecular composite of PC is required for its inhibition shown on LOX. Isothermal titration calorimetric study proves that one molecule of PC interacts with two molecules of LOX. Molecular dynamics simulation study pertaining to PC-LOX interactions shows it to be appropriate as a model to give molecular mechanistic insight into the varied biological properties of PC, demonstrated elsewhere in experimental studies including animal model studies. It explains that the PC-LOX interaction is of a function-freezing, protein-protein interaction in nature. The wide spectrum of properties of PC might be due to its function as a powerful protein hub showing non-specific protein-protein interactions.