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PDBsum entry 1jzf
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Electron transport
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PDB id
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1jzf
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Electron tunneling in single crystals of pseudomonas aeruginosa azurins.
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Authors
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B.R.Crane,
A.J.Di bilio,
J.R.Winkler,
H.B.Gray.
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Ref.
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J Am Chem Soc, 2001,
123,
11623-11631.
[DOI no: ]
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PubMed id
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Abstract
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Rates of reduction of Os(III), Ru(III), and Re(I) by Cu(I) in His83-modified
Pseudomonas aeruginosa azurins (M-Cu distance approximately 17 A) have been
measured in single crystals, where protein conformation and surface solvation
are precisely defined by high-resolution X-ray structure determinations: 1.7(8)
x 10(6) s(-1) (298 K), 1.8(8) x 10(6) s(-1) (140 K), [Ru(bpy)2(im)(3+)-];
3.0(15) x 10(6) s(-1) (298 K), [Ru(tpy)(bpy)(3+)-]; 3.0(15) x 10(6) s(-1) (298
K), [Ru(tpy)(phen)(3+)-]; 9.0(50) x 10(2) s(-1) (298 K), [Os(bpy)2(im)(3+)-];
4.4(20) x 10(6) s(-1) (298 K), [Re(CO)3(phen)(+)] (bpy = 2,2'-bipyridine; im =
imidazole; tpy = 2,2':6',2' '-terpyridine; phen = 1,10-phenanthroline). The time
constants for electron tunneling in crystals are roughly the same as those
measured in solution, indicating very similar protein structures in the two
states. High-resolution structures of the oxidized (1.5 A) and reduced (1.4 A)
states of Ru(II)(tpy)(phen)(His83)Az establish that very small changes in copper
coordination accompany reduction but reveal a shorter axial interaction between
copper and the Gly45 peptide carbonyl oxygen [2.6 A for Cu(II)] than had been
recognized previously. Although Ru(bpy)2(im)(His83)Az is less solvated in the
crystal, the reorganization energy for Cu(I) --> Ru(III) electron transfer
falls in the range (0.6-0.8 eV) determined experimentally for the reaction in
solution. Our work suggests that outer-sphere protein reorganization is the
dominant activation component required for electron tunneling.
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