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Anisotropic covalency contributions to superexchange pathways in type one copper active sites

Hadt, Ryan G. and Gorelsky, Serge I. and Solomon, Edward I. (2014) Anisotropic covalency contributions to superexchange pathways in type one copper active sites. Journal of the American Chemical Society, 136 (42). pp. 15034-15045. ISSN 0002-7863. PMCID PMC4210080. http://resolver.caltech.edu/CaltechAUTHORS:20180612-111103819

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Abstract

Type one (T1) Cu sites deliver electrons to catalytic Cu active sites: the mononuclear type two (T2) Cu site in nitrite reductases (NiRs) and the trinuclear Cu cluster in the multicopper oxidases (MCOs). The T1 Cu and the remote catalytic sites are connected via a Cys-His intramolecular electron-transfer (ET) bridge, which contains two potential ET pathways: P1 through the protein backbone and P2 through the H-bond between the Cys and the His. The high covalency of the T1 Cu-S(Cys) bond is shown here to activate the T1 Cu site for hole superexchange via occupied valence orbitals of the bridge. This covalency-activated electronic coupling (H_(DA)) facilitates long-range ET through both pathways. These pathways can be selectively activated depending on the geometric and electronic structure of the T1 Cu site and thus the anisotropic covalency of the T1 Cu-S(Cys) bond. In NiRs, blue (π-type) T1 sites utilize P1 and green (σ-type) T1 sites utilize P2, with P2 being more efficient. Comparing the MCOs to NiRs, the second-sphere environment changes the conformation of the Cys-His pathway, which selectively activates HDA for superexchange by blue π sites for efficient turnover in catalysis. These studies show that a given protein bridge, here Cys-His, provides different superexchange pathways and electronic couplings depending on the anisotropic covalencies of the donor and acceptor metal sites.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1021/ja508361hDOIArticle
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4210080/PubMed CentralArticle
https://pubs.acs.org/doi/suppl/10.1021/ja508361hPublisherSupporting Information
ORCID:
AuthorORCID
Hadt, Ryan G.0000-0001-6026-1358
Solomon, Edward I.0000-0003-0291-3199
Additional Information:© 2014 American Chemical Society. ACS AuthorChoice - This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes. Received: August 14, 2014. Published: October 1, 2014. This work was supported by NSF grant CHE-1360046 and NIH grant DK31450 (E.I.S.). R.G.H. acknowledges a Gerhard Casper Stanford Graduate Fellowship and the Achievement Rewards for College Scientists Foundation (ARCS). The authors declare no competing financial interest.
Funders:
Funding AgencyGrant Number
NSFCHE-1360046
NIHDK31450
Stanford UniversityUNSPECIFIED
ARCS FoundationUNSPECIFIED
PubMed Central ID:PMC4210080
Record Number:CaltechAUTHORS:20180612-111103819
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20180612-111103819
Official Citation:Anisotropic Covalency Contributions to Superexchange Pathways in Type One Copper Active Sites Ryan G. Hadt, Serge I. Gorelsky, and Edward I. Solomon Journal of the American Chemical Society 2014 136 (42), 15034-15045 DOI: 10.1021/ja508361h
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:87004
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:12 Jun 2018 18:24
Last Modified:12 Jun 2018 18:24

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