Investigation of affinity interaction between protein and triazine dye in reversed micelles with absorption spectra

The effect of protein on the absorption and its second derivative spectra of Cibacron Blue 3GA (CB) has been investigated in cationic reversed micelles compared with that in buffer solution. The spectra of CB is red-shifted with the addition of cetyltrimethylammonium bromide (CTAB) in buffer solution due to electrostatic interaction between CB and CTAB, while spectra of CB in the reversed micelles have no significant shift. The anionic CB has electrostatic interactions with cationic CTAB and has affinity interaction with bovine serum albumin (BSA) or lysozyme in the reversed micelles. The second derivative spectra of CB have red-shifted compared with the presence of BSA in the reversed micelles, which might indicate the decrease of the polarity of the CB microenvironment in the reversed micelles. The absorption maximum (λm) of CB with BSA in the reversed micelles was blue-shifted compared with that in buffer solution at pH<pI, which indicated that the affinity interaction between CB and protein is different from in reversed micelles and aqueous buffer solution. The CB microenvironment in the reversed micelles is more polar than that of buffer solution. The effect of lysozyme and BSA on the absorption spectra of CB in the reversed micelles has the same trend although these proteins differ in molecular weight and pI.