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Reactive sites and course of reduction in the Rieske protein
- Source :
- JBIC Journal of Biological Inorganic Chemistry. 22:545-557
- Publication Year :
- 2017
- Publisher :
- Springer Science and Business Media LLC, 2017.
-
Abstract
- Rieske proteins play an essential role in electron transfer in the bc 1 complex. Rieske proteins contain a [2Fe-2S] cluster with one iron ligated by two histidines and the other iron ligated by two cysteines. All Rieske proteins have pH-dependent reduction potentials with the histidines ligating the cluster deprotonating in response to increases in pH. The addition of diethylpyrocarbonate (DEPC) modifies deprotonated histidines. The previous studies on the isolated Thermus thermophilus Rieske protein have used large excesses of DEPC, and this study examines what amino acids become modified under different molar equivalents of DEPC to protein. Increasing amounts of DEPC result in more modification, and higher pH values result in faster reaction. Upon modification, the protein also becomes reduced and ~6 equivalents of DEPC are needed for 50% of the reduction to occur. Which amino acids are modified first also points to the most reactive species on the protein. Mass spectrometry analysis shows that lysine 68 is the most reactive amino acid, followed by the ligating histidine 154 and two other surfaces lysines, 76 and 43. The modification of the ligating histidine at low numbers of DEPC equivalents and correlation with a similar number of equivalents needed to reduce the protein shows that this histidine can interact with neighboring groups, and these results can be extended to the protein within the bc 1 complex, where interaction with neighboring residues or molecules may allow reduction to occur. These results may shed light on how Rieske transfers electrons and protons in the bc 1 complex.
- Subjects :
- Iron-Sulfur Proteins
Models, Molecular
0301 basic medicine
Circular dichroism
Stereochemistry
Lysine
Iron–sulfur cluster
010402 general chemistry
01 natural sciences
Biochemistry
Inorganic Chemistry
03 medical and health sciences
Electron transfer
chemistry.chemical_compound
Histidine
chemistry.chemical_classification
Molecular Structure
biology
Hydrogen-Ion Concentration
Thermus thermophilus
biology.organism_classification
0104 chemical sciences
Amino acid
030104 developmental biology
chemistry
Rieske protein
biology.protein
Oxidation-Reduction
Subjects
Details
- ISSN :
- 14321327 and 09498257
- Volume :
- 22
- Database :
- OpenAIRE
- Journal :
- JBIC Journal of Biological Inorganic Chemistry
- Accession number :
- edsair.doi.dedup.....999f5a4cb50025facbbc4ec3162f97b9