FEBS Letters | |
Assignment of haem ligands and detection of electronic absorption bands of molybdenum in the di‐haem periplasmic nitrate reductase of Paracoccus pantotrophus | |
Butler, Clive S.2  Cheesman, Myles R.2  Ferguson, Stuart J.1  Berks, Ben C.2  Richardson, David J.2  Thomson, Andrew J.2  | |
[1] Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK;Centre for Metalloprotein Spectroscopy and Biology, School of Biological and Chemical Sciences, University of East Anglia, Norwich NR4 7TJ, UK | |
关键词: Magnetic circular dichroism spectroscopy; Electron paramagnetic resonance spectroscopy; Heme ligand; Molybdoenzyme; MGD; molybdopterin guanine dinucleotide; NAP; periplasmic nitrate reductase; DMSOR; dimethyl sulfoxide reductase; EPR; electron paramagnetic resonance; MCD; magnetic circular dichroism; | |
DOI : 10.1016/S0014-5793(01)02577-7 | |
学科分类:生物化学/生物物理 | |
来源: John Wiley & Sons Ltd. | |
【 摘 要 】
The periplasmic nitrate reductase (NAP) from Paracoccus pantotrophus is a soluble two-subunit enzyme (NapAB) that binds two c-type haems, a [4Fe–4S] cluster and a bis-molybdopterin guanine dinucleotide cofactor that catalyses the reduction of nitrate to nitrite. In the present work the NapAB complex has been studied by magneto-optical spectroscopy to probe co-ordination of both the NapB haems and the NapA active site Mo. The absorption spectrum of the NapAB complex is dominated by features from the NapB c-type cytochromes. Using a combination of electron paramagnetic resonance spectroscopy and magnetic circular dichroism it was demonstrated that both haems are low-spin with bis-histidine axial ligation. In addition, a window between 600 and 800 nm was identified in which weak absorption features that may arise from Mo could be detected. The low-temperature MCD spectrum shows oppositely signed bands in this region (peak 648 nm, trough 714 nm) which have been assigned to S-to-Mo(V) charge transfer transitions.
【 授权许可】
Unknown
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