Cytosine Deuterium

CYTOSH. Trideutero-cytosine deuterium oxide solvate (neutron study at 82 K) (C4H2D3N30, D20). Weber HP, Craven BM, McMullan RK (1980) Acta Crystallogr, Sect B 36 645 CYTOSH01. THdeutero-cytosine deuterium oxide solvate (at 82 deg.K, X-ray and neutron studies) (C4H2D3N30, D20). Craven BM, Benci P, Epstein J, Fox RO, McMullan RK, Ruble JR, Stewart RF, Weber H-P (1979) Am Cryst Assoc, Ser 2, 7 42... 

Some other interesting observations regarding free radicals in these systems are noteworthy. In many instances, multiple conformations of radicals are found at lower but not higher temperatures. This indicates that the radicals exist in shallow energy wells at low temperature this phenomenon was observed very early, in the 4 K ENDOR investigation of radical formation in amino acids.23 Unlike the process in DNA. In which it is well understood that the thymine anion radical protonates at C6 to form T(C6)H-, in the crystalline state there is a not clear link between pyrimidine electron adducts and H-addition radicals. We finally note that a deuterium isotope effect of protonation/deprotonation processes was found in cytosine.HCl and 2 -deoxycytidine.HCl, as evidenced by a lower propensity for these processes to occur in partially deuterated systems than in predated ones. 

A study of the fragmentation pattern of deuterium and oxygen-18 labeled derivatives of cytosine nucleosides established that a major fragmentation process occurred that was absent in the spectra of other nucleosides. The various fragmentation pathways for prostaglandins A, B, E, and F were de-termined by the use of specific derivitization with d -tetramethylsilane. 

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