Ultraviolet and. gamma. -ray-induced free-radical reactions of nucleic acid constituents. Selectivity of some reactions for purines. Suppression of the reactivity of pyrimidines

Journal Article · Wed Sep 15 04:00:00 EDT 1976 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00435a041· OSTI ID:7142455

Frimer, A A; Havron, A; Leonov, D; Sperling, J; Elad, D

The photochemical reactions of purine and pyrimidine bases, nucleosides, nucleotides, and polynucleotides with 2-propanol, employing di-tert-butyl peroxide as initiator, were found to be selective for purines. The selectivity was shown to result from the suppression of the reactivity of the pyrimidines due to the presence of the purines. This was evidenced by comparison of the quantum yields for product formation, when the bases were allowed to react separately, to those in mixtures. In equimolar mixtures of pyrimidines and purines, the pyrimidine reactivity was suppressed, whereas that of the purine remained unchanged. The concentration and temperature dependence and the effect of anions on the degree of suppression of pyrimidine's reactivity in the presence of purines, as well as the correlation with changes in the osmotic coefficients upon dilution of mixtures, suggest that heteroassociation in the form of base-stacking is responsible for the effect. The thermally initiated reactions exhibit the same effect, thus indicating the general scope of the phenomenon.

• Research Organization: Weizmann Inst. of Science, Rehovot, Israel
• OSTI ID: 7142455
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 98:19; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
400500 -- Photochemistry
400600* -- Radiation Chemistry
ALCOHOLS
AZINES
CHEMICAL RADIATION EFFECTS
CHEMISTRY
ELECTROMAGNETIC RADIATION
GAMMA RADIATION
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
IONIZING RADIATIONS
NUCLEOSIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMISTRY
PROPANOLS
PURINES
PYRIMIDINES
QUANTITY RATIO
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIATIONS
RADICALS
RIBOSIDES
TEMPERATURE DEPENDENCE
ULTRAVIOLET RADIATION
YIELDS