Desulfovibrio vulgaris flavodoxin

Watenpaugh, K. D., Sieker, L. C., Jensen, L. H. A crystallographic structural study of the oxidation states of Desulfovibrio vulgaris flavodoxin. In Flavins and flavoproteins (Singer, T. P. ed.) pp. 405-410. Amsterdam, Elsevier 1976... 

The three-dimensional structures, or part of it, are also known for Desulfovibrio vulgaris and Anacystis nidulans flavodoxins. These results, including those obtained on C.MP., were recently summarized by Adman . Hence, these results will be discussed only briefly. The x-ray structures show that the isoalloxazine ring is embedded in a hydrophobic pocket of the apoprotein, i.e. flanked by at least one aromatic amino acid residue. During the redox transitions, especially from the oxidized to the semiquinone state, small conformational changes occur and contacts with the isoalloxazine ring are formed or broken. These conformational transitions form probably a kinetic barrier so that the semiquinone state is trapped by the apoprotein and, therefore, rather stable towards oxidation by molecular oxygen. 

If all the flavodoxins isolated from several species of Desulfovibrio are acidic, (low isoelectric points), the tetrahemic cytochromes cs are characterised by a wide range of pi values. The isoelectric points of the three cytochromes C3 studied in this work, D. vulgaris Miyazaki F, D, desulfuricans ATCC 27774 and D. gigas, are 9.5, 7.0 and 3.5, respectively. It is therefor interesting to compare the distribution of the electrostatic potential, over the surface of these proteins. The observed asymmetry of the surface charges was already emphasised in the case of D. vulgaris cytochrome C3 [Stewart et al., 1988] and was used as a basis to predict which of the four hemes should preferentially interact with D. vulgaris flavodoxin. 

Curley GP, Carr MC, Mayliew SG, Voordouw G (1991) Redox and flavin-binding properties of recombinant flavodoxin from Desulfovibrio vulgaris (hildenborough). Eur JBiochem 202 1091-1100... 

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