We report a combined theoretical and experimental study of ionization of cytosine monomers and dimers. Gas-phase molecules are generated by thermal vaporization of cytosine followed by expansion of the vapor in a continuous supersonic jet seeded in Ar. The resulting species are investigated by single photon ionization with tunable vacuum-ultraviolet (VUV) synchrotron radiation and mass analyzed...

Cytosine monohydrate (CM) and anhydrate crystal forms reversibly interconvert under high temperatures or humidity conditions. Here, we demonstrate through defect engineering the ability to expand thermal stability range of CM targeted creation quantifiable defects in low-level concentrations. Twelve different molecular dyes with a variety core structures charges were screened as potential dopan...

We describe procedures for determining cytosine and orotic acid in urine. We determine cytosine by cation-exchange analysis with either HCl or pH 5.2 buffer as eluent. Orotic acid is first separated by an anion-exchange separative procedure; after lyophilization, the product is subjected to "high-pressure" liquid chromatography for further separation and detection. We analyzed urine from normal...

Polarographie reduction of adenine and cytosine moieties in denatured DNA was followed by means of differential (derivative) pulse polarography. The measurements of the reduction currents yielded by samples of denatured DNA differing in guanine+cytosine (G + C) content showed that both cytosine and adenine residues were reduced in DNA in the pH range of 6.0 —8.7. The con­ tribution of their red...

We report resonant two-photon ionization spectra of laser desorbed, jet cooled, cytosine, 1-methyl cytosine, 5-methyl cytosine, and dimers of these. Unlike other pyrimidine bases, cytosine exhibits vibronic spectra with sharp features in two spectral regions, separated by about 5000 cm . We interpret these as being due to two tautomeric forms, one keto and one enol. The dimers absorb at wavelen...

While keto-amino cytosine is the dominant species in aqueous solution, spectroscopic studies in molecular beams and in noble gas matrices show that other cytosine tautomers prevail in apolar environments. Each of these offers two or three H-bonding sites (Watson-Crick, wobble, sugar-edge). The mass- and isomer-specific S1 ← S0 vibronic spectra of cytosine·2-pyridone (Cyt·2PY) and 1-methylcytosi...