TY - JOUR
T1 - Electronic properties of flavins
T2 - Implications on the reactivity and absorption properties of flavoproteins
AU - Wouters, Johan
AU - Durant, François
AU - Champagne, Benoît
AU - André, Jean-Marie
PY - 1997/12/1
Y1 - 1997/12/1
N2 - Electronic and structural properties of three protonated forms [HFlox, H22Flox
+(N5), and H2Flox
+(N1)] of lumiflavin have been determined at the HF/3-21G level of approximation. Larger delocalization and basicity explain the favorable protonation of N1 with respect to N5 whereas N1 protonation considerably activates the electrophilicity of N5 with respect to C4a. The relative position of the first electronic transition evaluated at the CNDO/CI level for the radicalar H2Fl+(N5) and H2Fl+(N1) structures further supports the classification of the flavoenzymes into two classes. Moreover, the π-π* transition has been correctly placed as the lowest energy transition for the neutral oxidized lumiflavin and predicts a blue shift of the low-lying electronic transition upon monoprotonation. Finally, from the analysis of the molecular complex between oxidized lumiflavin (HFlox) and hydroquinone, we have rationalized the complex formation in terms of the complementarity between the molecular electrostatic potentials as well as in terms of the overlap between the frontier orbitals involved in these charee transfer process.
AB - Electronic and structural properties of three protonated forms [HFlox, H22Flox
+(N5), and H2Flox
+(N1)] of lumiflavin have been determined at the HF/3-21G level of approximation. Larger delocalization and basicity explain the favorable protonation of N1 with respect to N5 whereas N1 protonation considerably activates the electrophilicity of N5 with respect to C4a. The relative position of the first electronic transition evaluated at the CNDO/CI level for the radicalar H2Fl+(N5) and H2Fl+(N1) structures further supports the classification of the flavoenzymes into two classes. Moreover, the π-π* transition has been correctly placed as the lowest energy transition for the neutral oxidized lumiflavin and predicts a blue shift of the low-lying electronic transition upon monoprotonation. Finally, from the analysis of the molecular complex between oxidized lumiflavin (HFlox) and hydroquinone, we have rationalized the complex formation in terms of the complementarity between the molecular electrostatic potentials as well as in terms of the overlap between the frontier orbitals involved in these charee transfer process.
KW - Ab initio calculations
KW - CIS/CNDO
KW - Electronic properties
KW - Flavins
KW - Reactivity of flavoproteins
UR - http://www.scopus.com/inward/record.url?scp=0000255148&partnerID=8YFLogxK
M3 - Article
AN - SCOPUS:0000255148
SN - 0020-7608
VL - 64
SP - 721
EP - 733
JO - International Journal of Quantum Chemistry
JF - International Journal of Quantum Chemistry
IS - 6
ER -