Model systems for flavoenzyme activity. Regulation of flavin recognition via modulation of receptor hydrogen-bond donor-acceptor properties

We have synthesized a new family of receptors for flavins based on 6-aryl-2,4-(acyldiamino)-s-triazines. In these synthetic hosts, systematic variation of the spatially remote substituents on the 6-aryl ring alters the hydrogen-bond-donating abilities of the amide functionality and the hydrogen-bond-accepting properties of the triazine N(3). This variation results in a strong modulation of the efficiency of flavin binding, with association constants for the receptor flavin complexes ranging over an 8-fold range.