The Mechanism of Proton Exclusion in Aquaporin Channels

Boaz Ilan, Emad Tajkhorshid, Klaus Schulten, Gregory A. Voth

Research output: Contribution to journalArticlepeer-review


The mechanism of proton exclusion in aquaporin channels is elucidated through free energy calculations of the pathway of proton transport. The second generation multistate empirical valence bond (MS-EVB2) model was applied to simulate the interaction of an excess proton with the channel environment. Jarzynski's equality was employed for rapid convergence of the free energy profile. A barrier sufficiently high to block proton transport is located near the channel center at the NPA motif-a site involved in bi-orientational ordering of the embedded water-wire in absence of the excess proton. A second and lower barrier is observed at the selectivity filter near the periplasmic outlet where the channel is narrowest. This secondary barrier may be essential in filtering other large solutes and cations.

Original languageEnglish (US)
Pages (from-to)223-228
Number of pages6
JournalProteins: Structure, Function and Genetics
Issue number2
StatePublished - May 1 2004


  • Aquaporin channels
  • Multistate empirical valence bond
  • Proton transport

ASJC Scopus subject areas

  • Genetics
  • Structural Biology
  • Biochemistry


Dive into the research topics of 'The Mechanism of Proton Exclusion in Aquaporin Channels'. Together they form a unique fingerprint.

Cite this