Effects of ultraviolet light on thymidine dinucleotide and polynucleotide
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TL;DR
The absorbance changes in dithymidylic acid and in polythymidy Alic acid produced by ultraviolet irradiation have been interpreted in terms of the reversible formation of dimers between adjacent thymine residues.
Abstract
1. The absorbance changes in dithymidylic acid and in polythymidylic acid produced by ultraviolet irradiation have been interpreted in terms of the reversible formation of dimers between adjacent thymine residues. The formation of dimers, breakage of dimers, and steady-state fraction of dimers are all wavelength dependent. 2. The action spectra for dimer formation are approximately the same as the absorption spectrum of thymine. The quantum yields are approx. 0.01 for dithymidylic-acid and approx. 0.02 for polythymidylic acid. 3. The action spectra for dimer breakage are the same for both polymers and are similar to that for breaking the thymine dimer. The quantum yield is approx. 1. 4. The steady-state fraction of dimers is approx. 70% for 280 mμ and approx. 15% for 240-mμ irradiation.