Electrochemical and spectrophotometric studies on dyes and proteins labelled with dyes

Electrochemical and fluorometric studies on a few selected phenazine and phenoxazine dyes has been carried out in free conditions and when covalently attached to a protein. The dyes have been coupled using the conventional coupling agent carbodiimide (derivative). Neutral Red and Nile Blue A, show significant shifts in their emission peaks to shorter wavelengths on binding to bovine serum albumin (BSA). Phenazine dyes such as Safranine O and Neutral Red show a shift in their formal redox potential to more positive potential on binding to BSA along with the two electron transfers taking place in a single step unlike incase of the free dyes where the two electron transfers take place at different potentials. Nile Blue A shows a negative shift in the reduction peak on covalently binding to BSA. These dyes when covalently coupled to the proteins mediate intramolecular electron transfers. (C) 2005 Published by Elsevier B.V.