Photoreactivities and thermal properties of psoralen cross-links.
We have studied the photoreaction of 8-methoxypsoralen (8-MOP), 4,5',8-trimethylpsoralen (TMP), and 4'-(hydroxymethyl)-4,5',8-trimethylpsoralen (HMT) with a pair of 18-base-long oligonucleotides in which a 14-base region is complementary. Only one 5'TpA site, favored for both monoadduct and cross-link formation with psoralen, is present in this oligonucleotide pair. We have used this model system to demonstrate, for the first time, strand specificity in the photoreaction of psoralen with DNA. We found that the two types of cross-links which form at this site have large differences in thermal stabilities. In addition, the denaturation of each cross-link isomer duplex occurred in at least three stages, which can be visualized as three bands in thermal equilibrium under the conditions of a denaturing polyacrylamide gel. This novel observation suggests that there are several domains differing in thermal stability in a psoralen cross-link.
Yeung
A T
AT
Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111.
Jones
B K
BK
Chu
C T
CT
D001483:Base Sequence; D011564:Furocoumarins; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis / Q000528:radiation effects; D010777:Photochemistry; D013329:Structure-Activity Relationship; D014307:Trioxsalen / Q000031:analogs & derivatives; D014466:Ultraviolet Rays
D011564:Furocoumarins; D009838:Oligodeoxyribonucleotides; D014307:Trioxsalen