1ls9

Structure of the Cytochrome c6 from the Green Alga Cladophora glomerata

spinqualitylabelsall models 1ls9, resolution 1.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1ls9 is a 1 chain structure with sequence from Cladophora glomerata. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: HEM Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum 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 This is a thorough biochemical, spectroscopic, electrochemical, and structural study of a cytochrome c(6) isolated from the filamentous green alga Cladophora glomerata. The protein sequence, elucidated using chemical and mass spectrometric techniques, features 91 amino acids and the characteristic CXXCH heme-binding motif found in c-type cytochromes. The protein is monomeric in both oxidation forms, thereby putting in question a functional role for protein dimerization. Direct electrochemical measurements established, for the first time, the kinetic and thermodynamic data for the redox process in a cytochrome c(6). In particular, the quasi-reversible and diffusion-controlled redox process is accompanied by negative enthalpy and entropy changes, resulting in an E degrees ' value of 0.352 V at 298 K. The pH-dependent properties of the oxidized protein, detected by UV-visible, NMR, and direct cyclic voltammetry, indicate the presence of two acid-base equilibria occurring in the acidic (pK(a) = 4.5) and alkaline regions (pK(a) = 9.0). NMR and electronic spectra allowed the assignment of these equilibria to deprotonation of heme propionate-7 and to replacement of the axial methionine with another ligand, respectively. The 1.3 A resolution X-ray structure of the oxidized protein, revealing a fold typical for class I cytochromes, suggests that the conserved Lys60 replaces the axial methionine at pH >9. The heme solvent accessibility is low, and no water molecules were found in the vicinity of the axial ligands of the heme Fe. A structure-based alignment of cytochromes c(6), and the direct comparison of their structures, indicate a substantial degree of identity between the tertiary structures and suggest patches involved in protein-protein interaction. In particular, the surface electrostatic potential of cytochromes c(6) features a hydrophobic region around the heme cofactor, and a backside surface rich in negative charges. Structural basis for the molecular properties of cytochrome c6.,Dikiy A, Carpentier W, Vandenberghe I, Borsari M, Safarov N, Dikaya E, Van Beeumen J, Ciurli S Biochemistry. 2002 Dec 17;41(50):14689-99. PMID:12475218 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Cytochrome c

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