Further consideration of flavin coenzyme biochemistry afforded by geometry-optimized molecular orbital calculations.

Investigation of lumiflavin and several other isoalloxazine ring derivatives has been carried out by geometry-optimized molecular orbital calculations. The results have provided insight into the flexibility of the flavin cofactor in the reduced and oxidized states, the regions of the fused three-ring system that should play an important role in flavin electron transfers, and the structural and functional role of the xylene and heteroatomic portions of the flavin system. The significance of these results is reviewed in relation to the experimentally identified chemical and biochemical properties of the flavin nucleotide coenzymes.