Asymmetry in the Ligand Coordination Sphere of the [FeFe] Hydrogenase Active Site Is Reflected in the Magnetic Spin Interactions of the Aza-propanedithiolate Ligand.

Autor: Reijerse EJ; Max-Planck-Institut für Chemische Energiekonversion , Stiftstrasse 34-36 , 45470 Mülheim an der Ruhr , Germany., Pelmenschikov V; Institut für Chemie , Technische Universität Berlin , Strasse des 17. Juni 135 , 10623 Berlin , Germany., Birrell JA; Max-Planck-Institut für Chemische Energiekonversion , Stiftstrasse 34-36 , 45470 Mülheim an der Ruhr , Germany., Richers CP; School of Chemical Sciences , University of Illinois , 600 South Mathews Avenue , Urbana , Illinois 61801 , United States., Kaupp M; Institut für Chemie , Technische Universität Berlin , Strasse des 17. Juni 135 , 10623 Berlin , Germany., Rauchfuss TB; School of Chemical Sciences , University of Illinois , 600 South Mathews Avenue , Urbana , Illinois 61801 , United States., Cramer SP; SETI Institute , Mountain View , California 94043 , United States., Lubitz W; Max-Planck-Institut für Chemische Energiekonversion , Stiftstrasse 34-36 , 45470 Mülheim an der Ruhr , Germany.
Jazyk: angličtina
Zdroj: The journal of physical chemistry letters [J Phys Chem Lett] 2019 Nov 07; Vol. 10 (21), pp. 6794-6799. Date of Electronic Publication: 2019 Oct 21.
DOI: 10.1021/acs.jpclett.9b02354
Abstrakt: [FeFe] hydrogenases are very active enzymes that catalyze the reversible conversion of molecular hydrogen into protons and electrons. Their active site, the H-cluster, contains a unique binuclear iron complex, [2Fe] H , with CN - and CO ligands as well as an aza-propane-dithiolate (ADT) moiety featuring a central amine functionality that mediates proton transfer during catalysis. We present a pulsed 13 C-ENDOR investigation of the H-cluster in which the two methylene carbons of ADT are isotope labeled with 13 C. We observed that the corresponding two 13 C hyperfine interactions are of opposite sign and corroborated this finding using density functional theory calculations. The spin polarization in the ADT ligand is shown to be linked to the asymmetric coordination of the distal iron site with its terminal CN - and CO ligands. We propose that this asymmetry is relevant for the enzyme reactivity and is related to the (optimal) stabilization of the iron-hydride intermediate in the catalytic cycle.
Databáze: MEDLINE
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