Spectroscopic study of molecular associations between FMN and β-carbolines

Article abstract of DOI:10.1016/0584-8539(93)80248-9

The spectrophotometric and thermodynamic properties of molecular complexes of flavin mononucleotide (FMN) (riboflavin 5'-phosphate) with some β-carboline derivatives have been investigated in aqueous solution.The molecular associations have been examined by means of electronic absorption spectra, since in each a new charge-transfer band has been located, and also the variation of the fluorescenece emission of FMN on the solutions has been observed.The formation constants for the molecular complexes were determined from absorption data using the Foster-Hammick-Wardley method.The quenching phenomenon observed in FMN fluorescence is related to the concentration of the β-carboline derivatives, allowing the calculation of the quenching constants for FMN-β-carboline complexes.Thermodynamic parameters have been determined from the values of association constants for the molecular complexes at various temperatures.The influence of substituents in the β-carboline molecule on the stability of the complexes formed was also investigated.