Photobinding of 8-methoxypsoralen to transfer RNA and 5-fluorouracil-enriched transfer RNA
- 1 March 1978
- journal article
- research article
- Published by American Chemical Society (ACS) in Biochemistry
- Vol. 17 (6), 1054-1059
- https://doi.org/10.1021/bi00599a018
Abstract
The photobinding of [3H]8MOP [8-methoxypsoralen] to tRNA upon irradiation at 365 nm in the absence of O2 was determined by gel filtration. The maximum photobinding was approximately 4 mol of 8MOP per mol of tRNA and 5FU[fluorouracil-enriched]-tRNA, with an overall quantum yield of 2.3 .times. 10-3. The photobinding kinetics for 8MOP-tRNA showed an apparent induction period or sigmoidal kinetic curve, indicating a specific initial photobinding site on tRNA which was identified as 4-thiouridine at position 8 from the 5''-end of Escherichia coli tRNA. Photobinding of 8MOP to 5FU-tRNA proceeded without an apparent induction period, 8MOP-tRNA and 8MOP-5FU-tRNA adducts were characterized by absorption, fluorescence and CD [circular dichroic] spectroscopy. A modified procedure was also developed to analyze the nucleoside composition in modified 8MOP-tRNA and 8MOP-5FU-tRNA. The results showed that 8MOP photochemically added mainly to pyrimidine bases. The photobinding of 8MOP changed the conformation (secondary in particular) of tRNA and inhibited aminoacyl-tRNA synthetase activity.This publication has 11 references indexed in Scilit:
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