2bzc | pdb_00002bzc

OXIDIZED AND REDUCED STRUCTURES OF A MUTANT PLASTOCYANIN OF FERN

spinqualitylabelsall models 2bzc, resolution 1.79Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2bzc is a 1 chain structure with sequence from Dryopteris crassirhizoma. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CU1 Related: 1kdi, 1kdj, 2bz7 Resources: FirstGlance, OCA, RCSB, PDBsum Function [PLAS_DRYCA] Participates in electron transfer between P700 and the cytochrome b6-f complex in photosystem I. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Plastocyanin is a small blue copper protein that shuttles electrons as part of the photosynthetic redox chain. Its redox behavior is changed at low pH as a result of protonation of the solvent-exposed copper-coordinating histidine. Protonation and subsequent redox inactivation could have a role in the down regulation of photosynthesis. As opposed to plastocyanin from other sources, in fern plastocyanin His90 protonation at low pH has been reported not to occur. Two possible reasons for that have been proposed: pi-pi stacking between Phe12 and His90 and lack of a hydrogen bond with the backbone oxygen of Gly36. We have produced this fern plastocyanin recombinantly and examined the properties of wild-type protein and mutants Phe12Leu, Gly36Pro, and the double mutant with NMR spectroscopy, X-ray crystallography, and cyclic voltammetry. The results demonstrate that, contrary to earlier reports, protonation of His90 in the wild-type protein does occur in solution with a pKa of 4.4 (+/-0.1). Neither the single mutants nor the double mutant exhibit a change in protonation behavior, indicating that the suggested interactions have no influence. The crystal structure at low pH of the Gly36Pro variant does not show His90 protonation, similar to what was found for the wild-type protein. The structure suggests that movement of the imidazole ring is hindered by crystal contacts. This study illustrates a significant difference between results obtained in solution by NMR and by crystallography. Protonation of a histidine copper ligand in fern plastocyanin.,Hulsker R, Mery A, Thomassen EA, Ranieri A, Sola M, Verbeet MP, Kohzuma T, Ubbink M J Am Chem Soc. 2007 Apr 11;129(14):4423-9. Epub 2007 Mar 17. PMID:17367139 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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