THE PHOTOREACTION BETWEEN FUROCOUMARINS AND VARIOUS DNA WITH DIFFERENT BASE COMPOSITIONS

Abstract
Abstract— The photoreactivity of psoralen and 8‐methylpsoralen towards various samples of DNA having different base‐pair compositions has been studied. The total photobinding capacity shown by the two furocoumarins increases by increasing the content of A‐T, confirming the data previously obtained using synthetic polynucleotides.The amount of monofunctional fluorescent 4′,5′‐cycloadducts and of the cross‐linkages formed during the photoreaction is not parallel to the content of A‐T, but is highest when the A‐T content is between 50 and 60%, while it decreases as the content of A‐T is lowered or increased. The possible binding site for the formation of 4′,5′‐monofunctional cycloadducts as well as of cross‐linkages is discussed.