Comparative effect of cationic gemini surfactant and its monomeric counterpart on the conformational stability of phospholipase A2

Abstract Herein, we have investigated the effect of cationic gemini surfactant (hexanediyl-α,ω-bis-(N-(2-hydroxyethyl) N-methylhexadecylammonium bromide), (16-6-16MEA) and its monomeric counterpart (N-(2-hyroxyethyl) N, N-dimethylhexadecylammonium bromide), (16MEA) on the conformational stability of phospholipase A 2 (PLA 2 ). The interaction of gemini surfactant and its monomeric counterpart with PLA 2 was characterized by utilizing steady-state fluorescence, time-resolved fluorescence, CD spectroscopy, and computational methods. The steady-state fluorescence results suggested the involvement of static quenching mechanism which was further supported by time resolved fluorescence measurements. The Stern-Volmer equation was utilized to calculate the value of Stern-Volmer quenching constant K SV . The stoichiometric binding ratio of PLA 2 with 16MEA and 16-6-16MEA was observed to be 1:1. The far-UV CD spectra for PLA 2 revealed similar alteration in secondary structure, in presence of 16MEA and 16-6-16 MEA, which was further supported by computational methods.