Change search
ReferencesLink to record
Permanent link

Direct link
Resonant Inelastic X-ray Scattering on Ferrous and Ferric bis-imidazole Porphyrin and Cytochrome c: Nature and Role of the Axial Methionine-Fe Bond
Stanford Univ, Dept Chem, Stanford, CA 94305 USA; Stanford Univ, SLAC Natl Accelerator Lab, Linac Coherent Light Source, Menlo Pk, CA 94025 USA.
Stanford Univ, Dept Chem, Stanford, CA 94305 USA.
Stanford Univ, Dept Chem, Stanford, CA 94305 USA.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Theoretical Chemistry. Stanford Univ, Dept Chem, Stanford, CA 94305 USA.ORCID iD: 0000-0002-1312-1202
Show others and affiliations
2014 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, no 52, 18087-18099 p.Article in journal (Refereed) Published
Abstract [en]

Axial Cu–S(Met) bonds in electron transfer (ET) active sites are generally found to lower their reduction potentials. An axial S(Met) bond is also present in cytochrome c (cyt c) and is generally thought to increase the reduction potential. The highly covalent nature of the porphyrin environment in heme proteins precludes using many spectroscopic approaches to directly study the Fe site to experimentally quantify this bond. Alternatively, L-edge X-ray absorption spectroscopy (XAS) enables one to directly focus on the 3d-orbitals in a highly covalent environment and has previously been successfully applied to porphyrin model complexes. However, this technique cannot be extended to metalloproteins in solution. Here, we use metal K-edge XAS to obtain L-edge like data through 1s2p resonance inelastic X-ray scattering (RIXS). It has been applied here to a bis-imidazole porphyrin model complex and cyt c. The RIXS data on the model complex are directly correlated to L-edge XAS data to develop the complementary nature of these two spectroscopic methods. Comparison between the bis-imidazole model complex and cyt c in ferrous and ferric oxidation states show quantitative differences that reflect differences in axial ligand covalency. The data reveal an increased covalency for the S(Met) relative to N(His) axial ligand and a higher degree of covalency for the ferric states relative to the ferrous states. These results are reproduced by DFT calculations, which are used to evaluate the thermodynamics of the Fe–S(Met) bond and its dependence on redox state. These results provide insight into a number of previous chemical and physical results on cyt c.

Place, publisher, year, edition, pages
2014. Vol. 136, no 52, 18087-18099 p.
National Category
Physical Chemistry
URN: urn:nbn:se:uu:diva-239173DOI: 10.1021/ja5100367ISI: 000347438300032PubMedID: 25475739OAI: diva2:773450
German Research Foundation (DFG), KR3611/2-1NIH (National Institute of Health), P41GM103393
Available from: 2014-12-19 Created: 2014-12-19 Last updated: 2016-10-27Bibliographically approved

Open Access in DiVA

fulltext(1394 kB)34 downloads
File information
File name FULLTEXT01.pdfFile size 1394 kBChecksum SHA-512
Type fulltextMimetype application/pdf

Other links

Publisher's full textPubMed

Search in DiVA

By author/editor
Lundberg, Marcus
By organisation
Theoretical Chemistry
In the same journal
Journal of the American Chemical Society
Physical Chemistry

Search outside of DiVA

GoogleGoogle Scholar
Total: 34 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 504 hits
ReferencesLink to record
Permanent link

Direct link