Theoretical study on charge-transfer interaction between acyl-CoA dehydrogenase and 3-thiaacyl-CoA using density functional method.
Acyl-CoA dehydrogenase forms a complex with a substrate analog, 3-thiaacyl-CoA, exhibiting a charge-transfer (CT) band. The structure of a complex model of oxidized lumiflavin with deprotonated 3-thiabutanoate ethylthioester designed for the above CT complex was fully optimized by means of density functional theory (DFT), the spatial arrangement being similar to the corresponding X-ray structure reported previously. The electrostatic interaction between flavin and an anionic ligand, therefore, plays a major role in determination of the arrangement of the CT complex. When the excitation energies and oscillator strengths for the optimized structures of complex models including oxidized 8-substituted lumiflavins were calculated, the obtained wavelengths correlated well with observed values reported. Subsequently, we carried out DFT calculations for new complex models redesigned for complexes of oxidized 8-substituted FADs with an anionic ligand by introducing hydrogen bonds at the carbonyl group of the ligand with the 2'-hydroxyl group of the N10-ribityl of FAD and with the main-chain amide group of Glu376. The CT absorbing wavelengths of the new complex models exhibited better correlation with those observed previously. Consequently, comparison of substituent effects on the DFT calculations for the complex models will lead to a deeper understanding of the CT interaction and the effect of the hydrogen-bonding interaction on the CT framework.
Tanaka
Takeyuki
T
Department of Biosystems Science, Graduate School of Science and Technology, Kobe University, 1-1 Rokodai-cho, Nada-ku, Kobe 657-8501. putaro@protein.osaka-u.ac.jp
Tamaoki
Haruhiko
H
Nishina
Yasuzo
Y
Shiga
Kiyoshi
K
Ohno
Takashi
T
Miura
Retsu
R
D042964:Acyl-CoA Dehydrogenase / Q000737:chemistry*; D044927:Electron-Transferring Flavoproteins / Q000737:chemistry; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry; D005415:Flavins / Q000737:chemistry; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D017433:Protein Structure, Secondary; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
D044927:Electron-Transferring Flavoproteins; D005415:Flavins; C001922:lumiflavin; D005182:Flavin-Adenine Dinucleotide; D042964:Acyl-CoA Dehydrogenase