| 13C ENDOR reveals that the D1 polypeptide C-terminus is directly bound to Mn in the photosystem II oxygen evolving complex. | |
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MedLine Citation:
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PMID: 20038096 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Antiferromagnetically coupled Mn(III)Mn(IV) dimers have been commonly used to study biological systems that exhibit complex exchange interactions. Such is the case for the oxygen evolving complex (OEC) in photosystem II (PSII), where we have studied whether the C-terminal carboxylate of D1-Ala344 is directly bound to the Mn cluster. To probe these protein-derived carboxylate hyperfine interactions, which give direct bonding information, Q-band (34 GHz) Mims ENDOR was performed on a Mn(III)Mn(IV) dimer ([Mn(III)Mn(IV)(mu-O)(2)mu-OAc(TACN)(2)](BPh(4))(2)) (1) that was labeled with (13)C (I = (1)/(2)) at the carboxylate position of the acetate bridge. A(dip) is computed based on atomic coordinates from available X-ray crystal structures to be [-2.4, -0.8, 3.2] MHz. The value for A(iso) was determined based on simulation of the experimental ENDOR data, for complex 1 A(iso) = -1 MHz. Similar studies were then performed on PSII from Synechocystis sp. PCC 6803, in which all alanine-derived C=O groups are labeled with (13)C including the C-terminal alpha-COO(-) group of D1 (Ala344), as well as PSII proteins uniformly labeled with (13)C. Using recent X-ray crystallography data from T. elongatus the values for A(dip) were calculated and simulations of the experimental data led to A(iso) values of 1.2, 1, and 2 MHz, respectively. We infer from complex 1 that an A(iso) significantly larger than 1.2 MHz for a Mn-coordinating carboxylate moiety is unlikely. Therefore, we support the closer arrangement of Ala344 suggested by the Loll and Guskov structures and conclude that the C-terminal carboxylate of D1 polypeptide is directly bound to the Mn cluster. |
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Authors:
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Jamie A Stull; Troy A Stich; Rachel J Service; Richard J Debus; Sanjay K Mandal; William H Armstrong; R David Britt |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S. |
Journal Detail:
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Title: Journal of the American Chemical Society Volume: 132 ISSN: 1520-5126 ISO Abbreviation: J. Am. Chem. Soc. Publication Date: 2010 Jan |
Date Detail:
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Created Date: 2010-01-14 Completed Date: 2010-03-26 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 7503056 Medline TA: J Am Chem Soc Country: United States |
Other Details:
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Languages: eng Pagination: 446-7 Citation Subset: IM |
Affiliation:
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Department of Chemistry, University of California-Davis, Davis, California 95616, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Carbon Isotopes Electron Spin Resonance Spectroscopy Manganese / chemistry* Peptides / chemistry* Photosystem II Protein Complex / chemistry*, metabolism |
| Grant Support | |
ID/Acronym/Agency:
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GM-076232/GM/NIGMS NIH HHS; GM-48242/GM/NIGMS NIH HHS; S10-RR021075/RR/NCRR NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Carbon Isotopes; 0/Peptides; 0/Photosystem II Protein Complex; 7439-96-5/Manganese |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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