ISSN:
1432-2099
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Physics
Notes:
Summary The angelicin-thymine photoadduct formed by irradiation (365 nm) of an aqueous solution of angelicin and tritiated thymine was isolated by preparative paper chromatography. Reirradiation of this photoadduct at wavelengths shorter than 334 nm splits the adduct, forming again the two parent compounds. A DNA-angelicin combination (8.30 μg angelicin per mg of DNA) was prepared by irradiating (365 nm) an aqueous solution of DNA with3H-angelicin. Reirradiation of this combination at wavelengths shorter than 312 nm releases3H-angelicin. The above mentioned conditions were employed to reactivate the photodamaged bacterial cells by angelicin. No reactivation was observed at shorter wavelengths; on the contrary, the lethality was higher after reirradiation. We conclude therefore, that the damage produced directly by the shorter wavelength radiations (formation of pyrimidine dimers) is greater than the small repair produced under our experimental conditions. Reirradiation of bacterial cells with visible light is a condition which activates the photoreactivating enzymes, which are able to provoke the cleavage of pyrimidine dimers. The inability to repair the photodamage caused by furocoumarins under these conditions suggests that this enzyme is highly specific for pyrimidine dimers. Though in both cases,i.e. pyrimidine-pyrimidine and pyrimidine-furocoumarine dimers a cyclo-butane ring is involved, the latter is not recognized by the photoreactivating enzyme.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01194255
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