%0 Journal Article %J Eur J Biochem %D 1994 %T Primary sequence, oxidation-reduction potentials and tertiary-structure prediction of Desulfovibrio desulfuricans ATCC 27774 flavodoxin %A Caldeira, J. %A Palma, P. N. %A Regalla, M. %A Lampreia, J. %A Calvete, J. %A Schafer, W. %A Legall, J. %A Moura, I. %A Moura, J. J. %K Amino Acid Sequence %K Base Sequence %K Desulfovibrio/*chemistry %K Electron Spin Resonance Spectroscopy %K Flavodoxin/*chemistry %K Hydrogen-Ion Concentration %K Molecular Sequence Data %K Oxidation-Reduction %K Protein Structure, Tertiary %K Sequence Homology, Amino Acid %K Spectrophotometry, Ultraviolet %K Spectrum Analysis %M 8143752 %P 987-95 %U http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=8143752 %V 220 %X

Flavodoxin was isolated and purified from Desulfovibrio desulfuricans ATCC 27774, a sulfate-reducing organism that can also utilize nitrate as an alternative electron acceptor. Mid-point oxidation-reduction potentials of this flavodoxin were determined by ultraviolet/visible and EPR methods coupled to potentiometric measurements and their pH dependence studied in detail. The redox potential E2, for the couple oxidized/semiquinone forms at pH 6.7 and 25 degrees C is -40 mV, while the value for the semiquinone/hydroquinone forms (E1), at the same pH, -387 mV. E2 varies linearly with pH, while E1 is independent of pH at high values. However, at low pH (< 7.0), this value is less negative, compatible with a redox-linked protonation of the flavodoxin hydroquinone. A comparative study is presented for Desulfovibrio salexigens NCIB 8403 flavodoxin [Moura, I., Moura, J.J.G., Bruschi, M. & LeGall, J. (1980) Biochim. Biophys. Acta 591, 1-8]. The complete primary amino acid sequence was obtained by automated Edman degradation from peptides obtained by chemical and enzymic procedures. The amino acid sequence was confirmed by FAB/MS. Using the previously determined tridimensional structure of Desulfovibrio vulgaris flavodoxin as a model [similarity, 48.6%; Watenpaugh, K.D., Sieker, L.C., Jensen, L.H., LeGall, J. & Dubourdieu M. (1972) Proc. Natl Acad. Sci. USA 69, 3185-3188], the tridimensional structure of D. desulfuricans ATCC 27774 flavodoxin was predicted using AMBER force-field calculations.

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0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't

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