Article: article from journal or magazin.
Diethyl pyrocarbonate: a chemical probe for secondary structure in negatively supercoiled DNA.
Proceedings of the National Academy of Sciences of the United States of America
Purine residues located within regions of DNA that have the potential to form left-handed Z-helical structures are modified preferentially by diethyl pyrocarbonate; this hyperreactivity is dependent on the degree of negative superhelicity of the circular DNA molecules. As negative superhelical density increases, guanosines in a 32-base-pair alternating G-C sequence and adenosines (but not guanosines) in a 64-base-pair alternating A-C/G-T sequence become 5- to 10-fold more reactive to diethyl pyrocarbonate. The negative superhelical densities at which enhanced reactivity occurs are similar to those reported for the point at which left-handed helices form within plasmids carrying these DNA sequences. Probing of negatively supercoiled pBR322 with diethyl pyrocarbonate reveals a hyperreactive region 31 base pairs in length of which only 9 base pairs are a perfect alternating purine and pyrimidine sequence; the reactivity of purines within this sequence indicates that purines in the anti conformation, or guanosines in the syn conformation with neighboring 3' thymidines, are not hyperreactive in the Z-DNA form.
Adenosine, Alkylation, Base Sequence, DNA, DNA, Superhelical, Diethyl Pyrocarbonate/diagnostic use, Formates/diagnostic use, Guanosine, Nucleic Acid Conformation, Purines, Structure-Activity Relationship
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