1f5c
From Proteopedia
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CRYSTAL STRUCTURE OF F25H FERREDOXIN 1 MUTANT FROM AZOTOBACTER VINELANDII AT 1.75 ANGSTROM RESOLUTION
Overview
Elucidating how proteins control the reduction potentials (E0') of [Fe--S], clusters is a longstanding fundamental problem in bioinorganic chemistry., Two site-directed variants of Azotobacter vinelandii ferredoxin I (FdI), that show large shifts in [Fe--S] cluster E0' (100--200 mV versus standard, hydrogen electrode (SHE)) have been characterized. High resolution X-ray, structures of F2H and F25H variants in their oxidized forms, and circular, dichroism (CD) and electron paramagnetic resonance (EPR) of the reduced, forms indicate that the overall structure is not affected by the mutations, and reveal that there is no increase in solvent accessibility nor any, reorientation of backbone amide dipoles or NH--S bonds. The structures, combined with detailed investigation of the variation of E0' with pH and, temperature, show that the largest increases in E0' result from the, introduction of positive charge due to protonation of the introduced His, residues. The smaller (50--100 mV) increases observed for the neutral form, are proposed to occur by directing a Hdelta+--Ndelta- dipole toward the, reduced form of the cluster.
About this Structure
1F5C is a Single protein structure of sequence from Azotobacter vinelandii with SO4, F3S and SF4 as ligands. Full crystallographic information is available from OCA.
Reference
Crystal structures of ferredoxin variants exhibiting large changes in [Fe-S] reduction potential., Chen K, Bonagura CA, Tilley GJ, McEvoy JP, Jung YS, Armstrong FA, Stout CD, Burgess BK, Nat Struct Biol. 2002 Mar;9(3):188-92. PMID:11875515
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