Wavelength dependence for the photoreactions of DNA-Psoralen monoadducts. 1. Photoreversal of monoadducts

Journal Article · Tue Jun 30 00:00:00 EDT 1987 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00387a008· OSTI ID:5934665

Shi, Y; Hearst, J E

The authors have studied the wavelength dependence for the photoreversal of a monoadducted psoralen derivative, HMT (4'(hydroxymethyl)-4,5',8-trimethylpsoralen), in a single-stranded deoxyoligonucleotide (5'-GAAGCTACGAGC-3'). The psoralen was covalently attached to the thymidine residue in the oligonucleotide as either a furan-side monoadduct, which is formed through the cycloaddition between the 4',5' double bond of the psoralen and the 5,6 double bond of the thymidine, or a pyrone-side monoadduct, which is formed through the cycloaddition between the 3,4 double bond of the psoralen and the 5,6 double bond of the thymidine. As a comparison, they have also investigated the wavelength-dependent photoreversal of the isolated thymidine-HMT monoadducts. All photoreversal action spectra correlate with the extinction spectra of the isolate monoadducts. In the case of the pyrone-side monoadduct, two absorption bands contribute to the photoreversal with a quantum yield of 2 x 10/sup -2/ at wavelengths below 250 nm and 7 x 10/sup -3/ at wavelengths from 287 to 314 nm. The incorporation of the monoadduct into the DNA oligomer had little effect upon the photoreversal rate. For the furan-side monoadduct at least three absorption bands contribute to the photoreversal. The quantum yield varied from 5 x 10/sup -2/ at wavelengths below 250 nm to 7 x 10/sup -4/ at wavelengths between 295 and 365 nm. In contrast to the case of the pyrone-side monoadduct, the incorporation of the furan-side monoadduct into the DNA oligomer reduced the photoreversal rate constant at wavelengths above 285 nm.

• Research Organization: Univ. of California, Berkeley
• OSTI ID: 5934665
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 26:13; ISSN BICHA
• Country of Publication: United States
• Language: English

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