Question

. If we increase the concentration of NaCl how will change the binding of our transcription factor to the DNA? How will change the melting point of DNA? Of course, explain.

Answer 1

1. With increasing salt concentration, ions concentration inctreases. With increasing ion concentration, the ions can actually intercat with the receptor in a way that competes with the ligands. Also, the ions in the salty solution assemble in a screeing cloud around the macromolecule that have the potential to bind. When this binding reaction occurs, tehre is relese of ions in the screening cloud, whihc results in an entropy increase. Moreover, thermodynamic data suggests that the protein-DNA interaction at high salt concentration is accompanied by the removal of large numbers of water molecules from the buried hydrophobic surface area. In addition, the involvement of ions appears to influence the binding which can be explained by binding of cations in the interface between the electrostatically negative lateral lobes on the protein and the negatively charged DNA.