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EFFECT OF BASE SEQUENCE ON THE ULTRAVIOLET IRRADIATION PRODUCTS OF DOUBLE‐STRANDED POLYNUCLEOTIDES CONTAINING BROMOURACIL AND ADENINE
Author(s) -
Ehrlich Melanie,
Riley Monica
Publication year - 1974
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1974.tb06562.x
Subject(s) - polynucleotide , irradiation , hyperchromicity , copolymer , absorbance , rnase p , chemistry , ultraviolet light , ultraviolet , exonuclease iii , photochemistry , polymer , dna , polymer chemistry , chromatography , biochemistry , organic chemistry , rna , materials science , escherichia coli , physics , optoelectronics , nuclear physics , gene
—The effects of ultraviolet irradiation of double‐stranded synthetic polynucleotides containing BrU and A have been investigated. Homopolymer pairs and alternating copolymers composed of either ribo‐ or deoxyribo‐nucleotides were prepared and were irradiated with either 313 nm or ˜ 285 nm light. Strand separation and a modest amount of strand breakage followed irradiation of the homopolymer pairs. Changes in the ultraviolet absorption spectra of the polymers during irradiation reflected the sum of hyperchromic increases caused by progressive strand separation and loss of absorbance caused by photoproduct formation. Extensive debromination occurred. An RNase digest of irradiated poly(rA)–poly 14 C(rBrU), analysed by column chromatography, showed components similar to those found previously upon irradiation of single‐stranded poly(rBrU). Little photoproduct was released by RNase digestion as mononucleotides. The major photoproduct was in the dinucleotide fraction, and may be 5,5′‐diuracil. Base sequence had a profound effect on the sensitivity of the polynucleotides. Irradiation of alternating copolymers with doses of light comparable to those that produced major photochemical changes in the homopolymer pairs brought about little if any change in the copolymers of alternating base sequence.