Dithymine photodimers and photodecomposition products of thymidylyl-thymidine induced by ultraviolet radiation from 150 to 300 nm.
Solid thymidylyl-(3'-->5')-thymidine (dTpdT) was irradiated in a vacuum with monochromatic photons from 150 to 300 nm; the photoproducts were analyzed quantitatively by high-performance liquid chromatography. The results of the experiment were as follows: (1) above 210 nm the major photoproducts were three dithymine photodimers [the cis-syn and trans-syn cyclobutane thymine dimers and the thymine (6-4) photoproduct]; below 210 nm, they were three photodecomposition products (thymine, thymidine 5'-monophosphate and thymidine 3'-monophosphate). This shows that 210 nm is the wavelength at which the major photoproducts change from dithymine photodimers (far-UV type) to photodecomposition products (X-ray type). (2) The yields of the three dithymine photodimers had a similar wavelength dependence with each other: the yields had a peak at 260 nm and gradually decreased toward shorter wavelengths to 150 nm. (3) The yields of the three photodecomposition products also had a very similar wavelength dependence with each other: the yields increased exponentially with a decrease in the wavelength. (4) The average ratios of the yield of the (6-4) photoproduct to that of the cis-syn dimer were 0.30 between 170 and 220 nm, but 0.16 between 240 and 290 nm.
Saitou
M
M
Biophysics Laboratory, College of Science, Rikkyo (St. Paul's) University, Tokyo, Japan.
Hieda
K
K
D004247:DNA / Q000528:radiation effects; D015226:Dinucleoside Phosphates / Q000528:radiation effects*; D010777:Photochemistry; D011740:Pyrimidine Dimers / Q000032:analysis*; D014466:Ultraviolet Rays
D015226:Dinucleoside Phosphates; D011740:Pyrimidine Dimers; C017758:thymidylyl-(3'-5')-thymidine; D004247:DNA