Protein interactions of Merocyanine 540: Spectroscopic and crystallographic studies with lysozyme as a model protein

► MC 540 interacts with hen egg white lysozyme in the ground state. ► Complex is formed by cooperative binding, van der Waal's and H-bond interactions. ► Above 1:3 M ratio of protein and ligand, MC 540 acts as a denaturant. ► Binding site of MC 540 with trans and cis conformations is on protein surface. ► MC 540 interacts with Trp123 and SO32- is stabilized by Arg125 of lysozyme.