title: Resonance Raman spectra of semiquinone forms of flavins bound to riboflavin binding protein.
abstract: The resonance Raman (RR) spectra of semiquinones of complexes of riboflavin or 8-methoxyriboflavin (8-OCH3-RF) with riboflavin binding protein (RBP) were observed. The RR spectrum of neutral semiquinone of riboflavin-RBP complex in H2O solution has an intense line at 1617 cm-1, not observed for oxidized riboflavin bound to RBP. The line at 1617 cm-1 does not shift in D2O solution. The absorption spectrum of semiquinone of 8-OCH3-RF bound to RBP has maxima at 586, 396, and 344 nm, and the RR spectrum doublet lines at 1623 and 1615 cm-1. In D2O solution, the 1623 cm-1 line does not shift, but the 1615 cm-1 line shifts to 1604 cm-1. The line around 1620 cm-1 for the flavin semiquinone will be useful in the determination of the redox state of flavin.
mesh_terms: D001665:Binding Sites; D002352:Carrier Proteins; D004529:Egg White; D026901:Membrane Transport Proteins; D010084:Oxidation-Reduction; D011485:Protein Binding; D011487:Protein Conformation; D012256:Riboflavin / Q000031:analogs & derivatives*; D013053:Spectrophotometry; D013059:Spectrum Analysis, Raman; D013329:Structure-Activity Relationship
chemical_list: D002352:Carrier Proteins; D026901:Membrane Transport Proteins; C019079:riboflavin-binding protein; C026889:8-methoxyriboflavin; D012256:Riboflavin