Home News About Us Contact Contributors Disclaimer Privacy Policy Help FAQ

Quick Search
My eDoc
Session History
Support Wiki
Direct access to
document ID:

          Institute: MPI für medizinische Forschung     Collection: Arbeitsgruppe Zimmermann     Display Documents

ID: 226324.0, MPI für medizinische Forschung / Arbeitsgruppe Zimmermann
Asymmetric Hydrogen−Bonding of the Quinone Cofactor in Photosystem I Probed by 13C−labeled Naphthoquinones
Translation of Title:Asymmetric Hydrogen−Bonding of the Quinone Cofactor in Photosystem I Probed by 13C−labeled Naphthoquinones
Authors:Pushkar, Yulia N.; Golbeck, John H.; Stehlik, Dietmar; Zimmermann, Herbert
Date of Publication (YYYY-MM-DD):2004-01-01
Title of Journal:J. Phys. Chem. B
Journal Abbrev.:J. Phys. Chem. B
Issue / Number:27
Start Page:9439
End Page:9448
Review Status:Peer-review
Audience:Experts Only
Intended Educational Use:No
Abstract / Description:In photosystem I (PS I) the phylloquinone secondary acceptor functions as a one electron gate similar to the QA quinone secondary acceptor in type II reaction centers. The quinone radical anion formed during charge separation as part of the P700+ A1− radical pair state is known to have a highly asymmetric electron spin density distribution, which is attributed to asymmetric hydrogen bonding with the protein environment. Here, the native phylloquinone is replaced by specifically 13C−labeled 2−methyl−1,4−naphthoquinones (2−methyl−4−13C−1,4−naphthoquinone and 2−13C−methyl−1,4−naphthoquinone) to probe the spin density distribution in two relevant quinone ring positions. The menB phylloquinone biosynthetic pathway mutant was used because it allows for efficient in vitro quinone replacement in isolated PS I trimers. X− and Q−band time−resolved EPR spectroscopy was used to determine the 13C hyperfine tensors in the functional P700+ A1− state. For 2−methyl−4−13C−1,4−naphthoquinone anion radical the largest hyperfine tensor component Azz = 44 MHz was found to be considerably larger than those determined in bacterial reaction centers. The PS I structure at 2.5 Å resolution shows a single H−bond from the backbone NH group of a specific leucine residue. Such a highly asymmetric H−bonding is confirmed here for the functional P700+ A1−state. Experimental evidence for an unusual backbone H−bond strength is analyzed by comparing the quinone binding site with that in bacterial reaction centers and possible mechanisms of increased H−bond strength are considered.
Last Change of the Resource (YYYY-MM-DD):--
External Publication Status:published
Document Type:Article
Communicated by:Wulf Kaiser
Affiliations:MPI für medizinische Forschung/Arbeitsgruppe Herbert Zimmermann
Relations:Has References-URI:http%3A%2F%2Fpubs.acs.org%2Fcgi-bin%2Fpubmed%2Fdb%3Dm%26form%3D6%26uid%3D12741819%26Dopt%3Dr
Has References-URI:http%3A%2F%2Fpubs.acs.org%2Fcgi-bin%2Fpubmed%2Fdb%3Dm%26form%3D6%26uid%3D11772039%26Dopt%3Dr
Has References-URI:http%3A%2F%2Fpubs.acs.org%2Fcgi-bin%2Fpubmed%2Fdb%3Dm%26form%3D6%26uid%3D9838060%26Dopt%3Dr
Has References-URI:http%3A%2F%2Fpubs.acs.org%2Fcgi-bin%2Fpubmed%2Fdb%3Dm%26form%3D6%26uid%3D8639614%26Dopt%3Dr
Has References-URI:http%3A%2F%2Fpubs.acs.org%2Fcgi-bin%2Fpubmed%2Fdb%3Dm%26form%3D6%26uid%3D10722690%26Dopt%3Dr
Full Text:
Sorry, no privileges
The scope and number of records on eDoc is subject to the collection policies defined by each institute - see "info" button in the collection browse view.