Reflectivity change adenine

When adenine was added to the solution, no appreciable change was found on the i—E curve (Figure 12, curve b, solid line), although the marked decrease in reflectivity was observed on the R/Rq—E curves in the potential region more positive than —0.8 V (curves d, e, and/in Fig. 12, in which the R/Ro—E curves are drawn separately to avoid their overlap). The reflectivity change was enhanced with the increase in the adenine concentration, but it tended to be saturated when the adenine concentration was more than 1 x M. 

Fig. 14. Concentration dependence of the reflectivity change due to the adsorption of adenine.

For any given tissue or cell preparation, it is desirable to compare the amount of radioisotope which the cyclic AMP contains with the absolute levels of the cyclic nucleotide. The result of such a comparison for heart tissue slices demonstrates that the radioactive cyclic AMP formed reflects the changes of the absolute levels of the cyclic nucleotide [113], A similar result has been obtained in brain slices [114,115]. Thus, the prelabelling method provides a convenient means of studying dynamic changes in cyclic AMP levels in tissues and cells. It is essential that cyclic AMP be isolated free of other labelled adenine products, and this involves fractionation on Dowex 50 columns and/or paper chromatography of the tissue extract. 

The adenine frequencies of S-adenosylmethionine and S-adenosylhomocysteine in acid solution are identical with one another and with those for adenosine under similar conditions (Tsuboi et al., 1962). The absorption bands due to the COO and GOOD of these compounds are also very close to one another. The small shift in the GOO band may reflect a slight perturbation by a relatively far removed sulfonium center. Glosely spaced groups lead to a larger change in frequency. 

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