Spectral and fluorescent study of the noncovalent interaction of a meso-substituted cyanine dye with serum albumins

A comparative study of the noncovalent interaction of the cyanine dye probe 3,3′-di-(γ-sulfopropyl)-4,5,4′,5′-dibenzo-9-ethylthiacarbocyanine betaine with serum albumins of different vertebrates: rat, rabbit, bovine, and human serum albumins (RSA, TSA, BSA, and HSA, respectively) has been performed by spectral and fluorescent methods. It has been shown that, the dye forms only one product, the trans-monomer bound to HSA, by interacting with HSA, whereas other binding products are also formed with other albumins. This is probably explained by a higher interaction energy of the dye with HSA than with other serum albumins.