Quantification and rationalization of the higher affinity of sodium over potassium to protein surfaces.

ABSTRACT: For a series of different proteins, including a structural protein, enzyme, inhibitor, protein marker, and a charge-transfer system, we have quantified the higher affinity of Na+ over K+ to the protein surface by means of molecular dynamics simulations and conductivity measurements. Both approaches show that sodium binds at least twice as strongly to the protein surface than potassium does with this effect being present in all proteins under study. Different parts of the protein exterior are responsible to a varying degree for the higher surface affinity of sodium, with the charged carboxylic groups of aspartate and glutamate playing the most important role. Therefore, local ion pairing is the key to the surface preference of sodium over potassium, which is further demonstrated and quantif

SUBMITTER: Vrbka L 

PROVIDER: S-EPMC2047604 | biostudies-literature | 2006 Oct

REPOSITORIES: biostudies-literature