THE SELF-ASSOCIATION OF FLAVIN MONONUCLEOTIDE (FMN2-) AS DETERMINED BY H-1-NMR SHIFT MEASUREMENTS

The concentration dependence of the H-1 NMR chemical upfield shifts of the protons H6, H9, H7 alpha, and H8 alpha of the 7,8-dimethylisoallo xazine residue of flavin mononucleotide (FMN2-) has been measured and the self-stacking tendency of FMN2- was quantified with the isodesmic model of indefinite non-cooperative self-association. The stacking ten dency of FMN2- is considerable and described in the concentration rang e of 0.0025-O.1 M with the indicated model by K = 27 +/- 15M(-1) (25 d egrees C; I = 0.1-0.3 M). This result is compared with related ones fr om the literature. The caveats regarding the self-stacking properties of FMN2- and their dependence on the concentration are discussed. (C) 1997 Elsevier Science B.V.