1d3w
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Crystal structure of ferredoxin 1 d15e mutant from azotobacter vinelandii at 1.7 angstrom resolution.
OverviewOverview
The basis of the chemiosmotic theory is that energy from light or, respiration is used to generate a trans-membrane proton gradient. This is, largely achieved by membrane-spanning enzymes known as 'proton pumps., There is intense interest in experiments which reveal, at the molecular, level, how protons are drawn through proteins. Here we report the, mechanism, at atomic resolution, for a single long-range electron-coupled, proton transfer. In Azotobacter vinelandii ferredoxin I, reduction of a, buried iron-sulphur cluster draws in a solvent proton, whereas, re-oxidation is 'gated' by proton release to the solvent. Studies of this, 'proton-transferring module' by fast-scan protein film voltammetry, high-resolution crystallography, site-directed mutagenesis and molecular, dynamics, reveal that proton transfer is exquisitely sensitive to the, position and pK of a single amino acid. The proton is delivered through, the protein matrix by rapid penetrative excursions of the side-chain, carboxylate of a surface residue (Asp 15), whose pK shifts in response to, the electrostatic charge on the iron-sulphur cluster. Our analysis defines, the structural, dynamic and energetic requirements for proton courier, groups in redox-driven proton-pumping enzymes.
About this StructureAbout this Structure
1D3W is a Single protein structure of sequence from Azotobacter vinelandii with SF4 and F3S as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Atomically defined mechanism for proton transfer to a buried redox centre in a protein., Chen K, Hirst J, Camba R, Bonagura CA, Stout CD, Burgess BK, Armstrong FA, Nature. 2000 Jun 15;405(6788):814-7. PMID:10866206
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