Interaction of ionic detergent cethyltrimethylammonium bromide with human serum albumin at various values of pH: Spectroscopic study

The interaction of cationic detergent cethyltrimethylammonium bromide (CTAB) with human serum albumin (HSA) at various values of pH has been studied using steady-state tryptophan fluorescence of HSA, polarized tryptophan fluorescence of HSA, fluorescence of nanomarker eosin in solutions of HSA and CTAB and Raman spectroscopy. By methods of fluorescent analysis the qualitative rearrangements of HSA globules at denaturation under action of CTAB are registered, whereas by Raman spectroscopy the quantitative changes of secondary structure of HSA at CTAB-induced denaturation are determined. It is shown that denaturation of HSA, taking place at interaction of cationic detergent CTAB with HSA, has one-stage character. At interaction of CTAB with HSA the deepest denaturation of HSA is reached at concentration of 4 mM CTAB (in the range of pH 3.5–8.0). More intensive denaturation of HSA under action of CTAB takes place at values of pH, higher than the isoelectric point of HSA (pI 4.7).