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8paz

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[[Image:8paz.gif|left|200px]]
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{{STRUCTURE_8paz| PDB=8paz | SCENE= }}
{{STRUCTURE_8paz| PDB=8paz | SCENE= }}
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'''OXIDIZED NATIVE PSEUDOAZURIN FROM A. FAECALIS'''
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===OXIDIZED NATIVE PSEUDOAZURIN FROM A. FAECALIS===
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==Overview==
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In order to understand the origins of differences in redox potentials among cupredoxins (small blue type I copper-containing proteins that reversibly change oxidation state and interact with redox partners), we have determined the structures of the native and two mutants (P80A and P80I) of pseudoazurin from Alcaligenes faecalis S-6 in oxidized and reduced forms at resolutions of 2.2 A in the worst case and 1.6 A in the best case. The P80A mutation creates a surface pocket filled by a new water molecule, whereas the P80I mutant excludes this water. Distinct patterns of change occur in response to reduction for all three molecules: the copper position shifts, Met 7 and Pro 35 move, and the relative orientations of residues 81 to 16, 18 to the amide planes of 77 and 86, all change. Systematic changes in the weak electrostatic interactions seen in the structures of different oxidation states can explain the Met 7/Pro 35 structural differences as well as some fluctuating solvent positions. Overall displacement parameters increase reversibly upon reduction. The reduced forms are slightly expanded over the oxidized forms. The geometries of the mutants become more trigonal in their reduced forms, consistent with higher redox potentials (+409 mV for P80A and +450 mV for P80I). Calculations of the differences in redox potentials, using POLARIS, reveal that a water unique to the P80A mutant is required (with correctly oriented hydrogens) to approximate the observed difference in redox potential. The POLARIS calculations suggest that the reduced forms are additionally stabilized through changes in the solvation of the copper center, specifically via the amides of residues 16, 39, 41, 79, and 80 which interact with either Phe 18, Met 86, or Cys 78. The redox potential of P80A is increased largely due to solvation effects, whereas the redox potential of P80I is increased largely due to geometrical effects.
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(as it appears on PubMed at http://www.pubmed.gov), where 9341204 is the PubMed ID number.
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{{ABSTRACT_PUBMED_9341204}}
==About this Structure==
==About this Structure==
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[[Category: Cuproprotein]]
[[Category: Cuproprotein]]
[[Category: Electron transfer]]
[[Category: Electron transfer]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri Jul 11 12:51:56 2008''

Revision as of 09:51, 11 July 2008

Image:8paz.png

Template:STRUCTURE 8paz

OXIDIZED NATIVE PSEUDOAZURIN FROM A. FAECALIS

Template:ABSTRACT PUBMED 9341204

About this Structure

8PAZ is a Single protein structure of sequence from Alcaligenes faecalis. This structure supersedes the now removed PDB entry 2paz. Full crystallographic information is available from OCA.

Reference

Site-directed mutants of pseudoazurin: explanation of increased redox potentials from X-ray structures and from calculation of redox potential differences., Libeu CA, Kukimoto M, Nishiyama M, Horinouchi S, Adman ET, Biochemistry. 1997 Oct 28;36(43):13160-79. PMID:9341204

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