Purines bases in DNA

These relationships are general. Hydroxyl-substituted purines and pyrimidines exist in their keto forms fflnino-substituted ones retain structures with an anino group on the ring. The pyrimidine and purine bases in DNA and RNA listed in Table 28.1 follow this general rule. Beginning in Section 28.7 we ll see how critical it is that we know the correct tautomeric forms of the nucleic acid bases. 

The hydrogen-bond pairing interactions between pyrimidine and purine bases in DNA and RNA. See DNA... 

The isothiochroman diradical 575 bearing a DNA intercalating aroyl moiety and formed during the cyclization of an ene-diyne has been demonstrated to preferentially cleave purine bases in DNA (Scheme 237) <1995JA4822>. 

A silver stain has been introduced that is 100 times more sensitive for proteins than Coomassie Blue, and 4 times more sensitive for nucleic acids than ethidium bromide.14 This stain is based on the reduction of Ag+ by thiol, tyrosine and amine functional groups in proteins and by the purine bases in DNA. The solid silver formed by reduction precipitates in the gel forming a permanent stain in the protein-nucleic acid zones, and is not reduced by bulfer or gel materials, so that... 

AP (apuiinic) site a site, lacking a purine base in DNA, that IS targeted by repair enzymes (10.5) arachidonic acid a fatty acid that contains 20 carbon atoms and 4 double bonds the precursor of prostaglandins and leukotrienes (8.8) aspartate transcarbamo)lase (ATCase) a classic example of an allosteric enzyme that catalyzes an early reaction in pyrimidine biosynthesis (6.5)... 

Haid Alkyl carbonium ions Benzylic carbonium ions Iminium ions Aldehydes Oxygen atoms of purine yrimidine bases in DNA Endocyclic nitrogens of purine bases in DNA Oxygen atoms of protein serine and threonine residues... 

Depurination Cleavage of the glycosidic bond between C-1 of deoxyribose and a purine base in DNA. Used in Maxam-Gilbert sequence analysis. 

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