Caldeira J, Palma PN, Regalla M, Lampreia J, Calvete J, Schäfer W, Legall J, Moura I, Moura JJ. Primary sequence, oxidation-reduction potentials and tertiary-structure prediction of Desulfovibrio desulfuricans ATCC 27774 flavodoxin.
EUROPEAN JOURNAL OF BIOCHEMISTRY 1994;
220:987-95. [PMID:
8143752 DOI:
10.1111/j.1432-1033.1994.tb18703.x]
[Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
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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