1ls9
From Proteopedia
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'''Structure of the Cytochrome c6 from the Green Alga Cladophora glomerata''' | '''Structure of the Cytochrome c6 from the Green Alga Cladophora glomerata''' | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Carpentier, W.]] | [[Category: Carpentier, W.]] | ||
| - | [[Category: | + | [[Category: Antiparallel beta-sheet]] |
| - | [[Category: | + | [[Category: Cytochrome]] |
| - | [[Category: | + | [[Category: Haem]] |
| - | [[Category: | + | [[Category: Heme]] |
| - | [[Category: | + | [[Category: Omega loop]] |
| - | [[Category: | + | [[Category: Protoporphyrin ix containing fe]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 00:14:11 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 21:14, 2 May 2008
Structure of the Cytochrome c6 from the Green Alga Cladophora glomerata
Overview
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.
About this Structure
1LS9 is a Single protein structure of sequence from Cladophora glomerata. Full crystallographic information is available from OCA.
Reference
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 Page seeded by OCA on Sat May 3 00:14:11 2008
