Energetics of single-file water transport

Abstract

The energetics of single-file water transport through membrane channels has remained enigmatic. Reports about increased water ordering in nanopores suggest a reduction in entropy. In contrast, a dangling OH-bond per water in a single-file configuration provides additional degrees of freedom, thus advocating increased entropy for intraluminal water molecules. The energetic expense for partial water dehydration - from four H-bonding partners in bulk water to two within the channel lumen - has remained equally controversial.