Conversion of psoralen DNA monoadducts in E. coli to interstrand DNA cross links by near UV light (320-360 nm): inability of angelicin to form cross links, in vivo.

Both angelicin and psoralen monoadducts formed in vivo in E. coli by near UV light produce lethal and mutagenic effects. However psoralen monoadducts are converted to cross links by higher doses of UV; angelicin monoadducts are not. The relevance of these results to psoralen photosensitization is discussed.