Forthcoming Events

23.01.2019 - 25.01.2019, DESY-Hamburg and European XFEL, Schenefeld, Germany
09.02.2019 - 13.02.2019, Banff Centre, Alberta, Canada

News

New scientific highlights- by MUST PIs Majed Chergui and Steve Johnson
The FP-RESOMUS Grant Agreement- now signed by the ETH Zürich and the European Commission
Cluster of Excellence RESOLV extended- our partner in FP-RESOMUS and the biannual Science and Gender Meetings
Kontext - A radio broadcast with Ursula Keller and Aline Rickli - on leadership positions for women in science (in German)
Nobel Prize in Physics 2018 for groundbreaking inventions: intense ultrafast laser pulses and optical tweezers
Ambizione grant awarded to Elsa Abreu- in Steve Johnson's group
Fabrizio Carbone promoted Associate Professor of Physics- in the EPFL School of Basic Sciences from 1st of August
New scientific highlights- by MUST PIs Ursula Keller, Gebhard Schertler / Jörg Standfuss, Majed Chergui, Peter Hamm
White Paper Photonics Switzerland- presented June 20, 2018 at the Swissmem "Industrietag"

Sequential Proton Coupled Electron Transfer (PCET)

March 23, 2016

Dynamics Observed over 8 Orders of Magnitude in Time

 
Charge transfer mechanisms lay at the heart of chemistry and biochemistry. Proton coupled electron transfers (PCET) are central in biological processes such as photosynthesis and in the respiratory chain, where they mediate long-range charge transfers. These mechanisms are normally difficult to harness experimentally due to the intrinsic complexity of the associated biological systems. Metal-peptide cations experience both electron and proton transfers upon photoexcitation, proving an amenable model system to study PCET.
 

The authors report on a time-resolved experiment designed to follow this dual charge transfer kinetics in [HG3W+Ag]+ (H = histidine, G = glycine, W = tryptophan) on time scales ranging from femtoseconds to milliseconds. While electron transfer completes in less than 4 ps, it triggers a proton transfer lasting over hundreds of microseconds.

Molecular dynamics simulations conducted in the group of Markus Meuwly show that the rate of formation of a PT-reactive structure (H-bond between indoleNH on tryptophan and imidazoleN on histidine) strongly depends on the initial peptide structure. In particular, while this rate is in the nanosecond range when starting from an extended conformation, it is considerably longer when starting from compact peptide conformations as in the initial metal complex. In other words, molecular dynamics simulations show that conformational dynamic plays an important role in slowing down this reaction.

The experimental study covers 8 orders of magnitude in time and shows that the 4 ps electron transfer induces a proton transfer hundreds of microseconds later. The combined experimental and computational approach provides a view of PCET as a single phenomenon despite its very wide time-domain span.

Reference: MacAleese, L., S. Hermelin, K. El Hage, P. Chouzenoux, A. Kulesza, R. Antoine, L. Bonacina, M. Meuwly, J.-P. Wolf and P. Dugourd (2016). Sequential Proton Coupled Electron Transfer (PCET): Dynamics Observed over 8 Orders of Magnitude in Time. J. Am. Chem. Soc. (10.1021/jacs.5b12587) MacAleese-2016 (807 KB).
 
back <<
NCCR MUST Office : ETHZ IQE/ULP-HPT H3 | Auguste-Piccard-Hof 1 | 8093 Zurich | E-Mail | +41 44 633 36 02
The National Centres of Competence in Research (NCCR) are a research instrument of the Swiss National Science Foundation
FNSNF