Helix → β conformational transition of poly(<scp>L</scp>‐lysine) on dye binding

Abstract

Abstract Binding of an azo dye, 4′‐dimethyl amino azo benzene‐4‐carboxylic acid (DAAC) to poly( L ‐lysine) (PLL) in basic aqueous solutions at 20°C has been studied. The azo dye was found to bind to PLL when its side‐chain amino groups are in the uncharged state. This was found to be a cooperative phenomenon, and the binding constant and cooperativity factor have been evaluated. The binding of the dye was found to result in a conformational transition of PLL from the α‐helix to the β‐sheet, which in turn helps in increased dye binding.