Interaction of Bovine (BSA), Rabbit (RSA), and Porcine (PSA) Serum Albumins with Cationic Single-Chain/Gemini Surfactants: A Comparative Study

The interactions among bovine, rabbit, and porcine serum albumins and single-chain cationic surfactant cetyltrimethylammonium bromide (CTAB) versus its gemini counterpart (designated as G4) have been studied. The studies were carried out in an aqueous medium at pH 7.0 using UV, intrinsic and extrinsic fluorescence spectroscopy, and far-UV circular dichroism techniques. The results indicate that compared to CTAB. G4 interacts strongly with the serum albumins, resulting in a significantly larger unfolding or decrease in alpha-helical content as reflected by the significantly larger decrease in ellipticity in the far-UV range. Unlike CTAB, a remarkable increase in the a-helical content of BSA at 625 mu M G4 and at 250 mu M G4 for RSA and PSA is observed. The appearance of conformational changes and saturation points in the proteins occurs at considerably lower [G4] compared to [CTAB]. The results obtained from the multi-technique approach are ascribed to the stronger forces in G4 owing to the presence of two charged headgroups and two hydrocarbon tails. Keeping the results in view, it is suggested that the gemini surfactants may be effectively used in the renaturation of proteins produced in genetically engineered cells via the artificial chaperone protocol and may also prove useful in drug delivery as solubilizing agents to recover proteins from insoluble inclusion bodies.