The Identification and Estimation of Pentose in Nucleic Acids and Nucleoproteins

Pentoses---A number of pentoses were examined by the carbazole procedure as previously described (1). The Evelyn photoelectric filter photometer (3) was again employed, with filters transmitting maximally at 660, 540, 520, and 420 rnp. In contrast to the color characteristics of the hexoses obtained after treatment with sulfuric acid and carbazole, the pentoses gave rise to colored solutions which, when tested with our filters, absorbed more strongly at 520 rnp than at 540 mp. In Table I are listed the e. values obtained at 520 and 420 mp for a number of pentoses as well as the calculated ratios EG~O/E~~~. There was good proportionality between the absorption measured at 520 rnp and the concentration of pentose. The ratios obtained with arabinose, ribose, and lyxose are very similar, so that they cannot be distinguished qualitatively from one another by this method. Xylose, on the other hand, yielded a very different ratio and can accordingly be readily distinguished from the other pentoses. Identification of Pentose in Nucleosides, Nucleotides, and Nucleic Acids-Adenosine, guanosine, uridine, adenylic acid, and guanylic acid (Table II) yielded E 520 / ~420 ratios which agreed closely with the