DNA unwinding induced by photoaddition of psoralen derivatives and determination of dark-binding equilibrium constants by gel electrophoresis

AUTOR(ES)

Wiesehahn, Gary

RESUMO

Derivatives of furo[3,2-g]coumarin (psoralen) can bind to the DNA double helix and, in the presence of long-wavelength UV light, the bound psoralen may react covalently with pyrimidine residues on one or both strands of the helix. By using agarose gel electrophoresis, we have determined the unwinding angle associated with each of four different psoralen derivatives to be 28° ± 4°. For 4,5′,8-trimethylpsoralen (trioxsalen) the unwinding angle was found to be independent of the initial DNA superhelix density in the range that is accessible to agarose gel electrophoresis.

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