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Rapid X-ray photore...
Rapid X-ray photoreduction of dimetal-oxygen cofactors in ribonucleotide reductase.
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- Sigfridsson Clauss, Kajsa (författare)
- Lund University,Lunds universitet,MAX IV-laboratoriet,MAX IV Laboratory
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Chernev, Petko (författare)
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Leidel, Nils (författare)
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- Popovic-Bijelic, Ana (författare)
- Stockholms universitet,Institutionen för biokemi och biofysik
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- Gräslund, Astrid (författare)
- Stockholms universitet,Institutionen för biokemi och biofysik
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Haumann, Michael (författare)
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Sigfridsson, Kajsa G. V. (författare)
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(creator_code:org_t)
- 2013
- 2013
- Engelska.
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Ingår i: Journal of Biological Chemistry. - 1083-351X .- 0021-9258.
- Relaterad länk:
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http://dx.doi.org/10...
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https://doi.org/10.1...
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https://lup.lub.lu.s...
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https://doi.org/10.1...
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https://urn.kb.se/re...
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Abstract
Ämnesord
Stäng
- Prototypic dinuclear metal cofactors with varying metallation constitute a class of O2-activating catalysts in numerous enzymes such as ribonucleotide reductase (RNR1). Reliable structures are required to unravel the reaction mechanisms. However, protein crystallography data may be compromised by X-ray photoreduction (XPR). We studied XPR of Fe(III)Fe(III) and Mn(III)Fe(III) sites in the R2 subunit of Chlamydia trachomatis RNR using X-ray absorption spectroscopy. Rapid and biphasic XPR kinetics at 20 K and 80 K for both cofactor types suggested sequential formation of (III,II) and (II,II) species and similar redox potentials of Fe and Mn sites. Comparing with typical X-ray doses in crystallography implies that (II,II) states are reached in <1 s in such studies. First-sphere metal coordinations and metal-metal distances differed after chemical reduction at room temperature and after XPR at cryogenic temperatures, as corroborated by model structures from density functional theory calculations. The inter-metal distances in the (II,II) states, however, are similar to R2 crystal structures. Therefore, crystal data of initially oxidized R2-type proteins mostly contain photoreduced (II,II) cofactors, which deviate from the native structures functional in O2-activation, explaining observed variable metal ligation motifs. This situation may be remedied by novel femtosecond free-electron-laser protein crystallography techniques.
Ämnesord
- NATURVETENSKAP -- Fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences (hsv//eng)
- NATURVETENSKAP -- Biologi -- Biokemi och molekylärbiologi (hsv//swe)
- NATURAL SCIENCES -- Biological Sciences -- Biochemistry and Molecular Biology (hsv//eng)
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- ref (ämneskategori)
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