Kinesin ATP Hydrolysis Requires Proton Tunneling within the Zundel Cation and a Second Proton Transfer

Abstract

Occurring between hydrogen-bonded networks of polar residues and water molecules, proton transfer reactions are essential in energy conversion, transduction, and storage in biological systems. Here, we determine the contribution of proton transfer to the biological acceleration of ATP hydrolysis in kinesins. A novel two-water cluster, or a Zundel cation, was observed to be hydrogen-bonded to a salt bridge in the kinesin motor protein active site. Solvent kinetic isotope experiments showed proton abstraction from the two-water cluster commits kinesin to catalysis.