The transfer of protons in water wires inside proteins.

The translocation of protons across membrane proteins is an essential phenomenon in biology. Only in recent years however, have we started to study in detail some of the basic features of proton transfer in water molecules inside proteins at the single molecule level. Due to their truly unique features, gramicidin-based ion channels have been used to probe proton transfer in both experimental and computational fronts. In this article, some of the new experimental findings on proton transfer in water molecules inside proteins will be reviewed. The results, their interpretations, and the perspectives toward the understanding of structure-function illations of proton transfer in proteins are discussed.