A Time-Resolved Iron-Specific X-ray Absorption Experiment Yields No Evidence for an Fe2+ Fe3+ Transition durin
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- 作者：Sabine Hermes ; Oliver Bremm ; Florian Garczarek ; Valerie Derrien ; Peter Liebisch ; Paola Loja ; Pierre Sebban ; Klaus Gerwert ; and Michael Haumann
- 刊名：Biochemistry
- 出版年：2006
- 出版时间：January 17, 2006
- 年：2006
- 卷：45
- 期：2
- 页码：353 - 359
- 全文大小：160K
- 年卷期：v.45,no.2(January 17, 2006)
- ISSN：1520-4995
文摘
Previous time-resolved FTIR measurements suggested the involvement of an intermediarycomponent in the electron transfer step QA- 
QB in the photosynthetic reaction center (RC) fromRhodobacter sphaeroides [Remy and Gerwert (2003) Nat. Struct. Biol. 10, 637]. By a kinetic X-rayabsorption experiment at the Fe K-edge we investigated whether oxidation occurs at the ferric non-hemeiron located between the two quinones. In isolated reaction centers with a high content of functional QB,at a time resolution of 30 
s and at room temperature, no evidence for transient oxidation of Fe wasobtained. However, small X-ray transients occurred, in a similar micro- to millisecond time range as inthe IR experiments, which may point to changes in the Fe ligand environment due to the charges on QA-and QB-. In addition, VIS measurements agree with the IR data and do not exclude an intermediate in theQA- QB transition.
QB in the photosynthetic reaction center (RC) fromRhodobacter sphaeroides [Remy and Gerwert (2003) Nat. Struct. Biol. 10, 637]. By a kinetic X-rayabsorption experiment at the Fe K-edge we investigated whether oxidation occurs at the ferric non-hemeiron located between the two quinones. In isolated reaction centers with a high content of functional QB,at a time resolution of 30 s and at room temperature, no evidence for transient oxidation of Fe wasobtained. However, small X-ray transients occurred, in a similar micro- to millisecond time range as inthe IR experiments, which may point to changes in the Fe ligand environment due to the charges on QA-and QB-. In addition, VIS measurements agree with the IR data and do not exclude an intermediate in theQA- QB transition.