Spectroscopic studies on the interaction of cationic surfactants with bovine serum albumin.
The interaction of the cationic surfactant cetyltrimethylammonium bromide (CTAB) with bovine serum albumin (BSA), a globular protein, has been studied by small-angle neutron scattering (SANS), fluorescence and circular dichroism (CD). SANS measurements show that at low [CTAB] the protein shows a native-like behavior. On the other hand, at high [CTAB], surfactant molecules result in the formation of a fractal structure representing a 'necklace model' of micelle-like clusters randomly distributed along the polypeptide chain. The overall size of the complex increases and the fractal dimension decreases on increasing the surfactant concentration. The size of the micelle-like clusters does not show any considerable change while the number of such clusters and their aggregation number increases with increasing [CTAB]. Some extrapolatory experiments were performed with tetradecyltrimethylammonium bromide (TTAB) and the surfactant was found to behave similarly leading to an increase in the size of protein along the semi-major axis at low concentrations and formation of a fractal structure at high concentrations. The fluorescence studies undertaken were found to be consistent with the SANS measurements. Native-like behavior of the protein mixed with low concentration of the surfactant was also concluded from the circular dichroism (CD) spectra where the spectra in presence of high [CTAB] could not be monitored because of high dynode voltage.
Gull
Nuzhat
N
Department of Chemistry, Aligarh Muslim University, Aligarh 202002, India.
Chodankar
Shirish
S
Aswal
V K
VK
Sen
Priyankar
P
Khan
Rizwan Hasan
RH
Kabir-ud-Din
D000817:Anilino Naphthalenesulfonates / Q000378:metabolism; D000818:Animals; D002412:Cations; D002417:Cattle; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000378:metabolism*; D002942:Circular Dichroism; D006863:Hydrogen-Ion Concentration; D033363:Neutron Diffraction; D017433:Protein Structure, Secondary; D053838:Scattering, Small Angle; D012710:Serum Albumin, Bovine / Q000737:chemistry / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013501:Surface-Active Agents / Q000378:metabolism*; D013696:Temperature; D050337:Trimethyl Ammonium Compounds / Q000378:metabolism*
D000817:Anilino Naphthalenesulfonates; D002412:Cations; D002593:Cetrimonium Compounds; D013501:Surface-Active Agents; D050337:Trimethyl Ammonium Compounds; D012710:Serum Albumin, Bovine; C027132:1-anilino-8-naphthalenesulfonate; C009410:tetradecyltrimethylammonium; D000077286:Cetrimonium