Redox potential difference between Desulfovibrio vulgaris and Clostridium beijerinckii flavodoxins.
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.
Ishikita
Hiroshi
H
Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA. hzi1@usc.edu
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
D024342:Amino Acids, Acidic; D001059:Apoproteins; D005418:Flavodoxin; D010710:Phosphates; C026932:apoflavodoxin; D005486:Flavin Mononucleotide; D012256:Riboflavin