title: Redox potential difference between Desulfovibrio vulgaris and Clostridium beijerinckii flavodoxins.
abstract: The redox potential of the flavin mononucleotide (FMN) hydroquinones for one-electron reduction in the Desulfovibrio vulgaris ( D. vulgaris) flavodoxin ( E sq/hq for FMNH (*)/FMNH (-)) was calculated using the crystal structure of the relevant hydroquinone form and compared to the results of the Clostridium beijerinckii ( C. beijerinckii) flavodoxin. In D. vulgaris and C. beijerinckii flavodoxins, the protein side chain causes significant downshifts of 170 and 240 mV in E sq/hq, respectively. In the C. beijerinckii flavodoxin, the E sq/hq downshift because of the protein side chain is essentially compensated by the counter influence of the protein backbone ( E sq/hq upshift of 260 mV). However, in the D. vulgaris flavodoxin, the corresponding protein backbone influence on E sq/hq is significantly small, i.e., less than half of that in the C. beijerinckii flavodoxin. In particular, there is a significant difference in the influence of the protein backbone of the so-called 60s loop region between the two flavodoxins. The E sq/hq difference can be best explained by the lower compensation of the side chain influence by the backbone influence in the D. vulgaris flavodoxin than in the C. beijerinckii flavodoxin.
authors: Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA. hzi1@usc.edu
authors: Hiroshi
authors: H
authors: Ishikita
mesh_terms: D000595:Amino Acid Sequence; D024342:Amino Acids, Acidic / Q000737:chemistry; D001059:Apoproteins / Q000737:chemistry; D046970:Clostridium beijerinckii; D016969:Desulfovibrio vulgaris; D005486:Flavin Mononucleotide / Q000737:chemistry*; D005418:Flavodoxin / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010710:Phosphates / Q000737:chemistry; D011487:Protein Conformation; D012256:Riboflavin / Q000737:chemistry; D016415:Sequence Alignment
chemical_list: D024342:Amino Acids, Acidic; D001059:Apoproteins; D005418:Flavodoxin; D010710:Phosphates; C026932:apoflavodoxin; D005486:Flavin Mononucleotide; D012256:Riboflavin