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188 THE PROTEIN SUBSTANCES.
cells appear in such places as were before endowed in a relatively poor
manner. As an example of this, the blood, in leucaemia, is extremely rich
in leucocytes. In such blood Kossel 1
found 1.04 p. m. purine bases,
against only traces in the normal blood. That these bases are also inter-
mediate steps in the formation of uric acid in the animal organism is
probable, and will be shown later (see Chapter XIV).
Only a few of the purine bases have been found in the urine or in the
muscles. Only four bases—xanthine, guanine, hypoxanthine, and ade-
nine—have been obtained, thus far, as cleavage products of nucleins,
and these do not always have a primary origin. In regard to the purine
bodies from other substances we refer the reader to their respective
chapters. Only the above four bodies, the real nuclein bases, will be
considered at this time.
Of these four bodies, xanthine and guanine form one special group
and hypoxanthine and adenine another. By the action of nitrous acid
guanine is converted into xanthine and adenine into hypoxanthine.
C5H4N40.NH+HN02 = C5H4N402+N2+H20;
Guanine Xanthine
C5H4N4.NH+HNO2+C5H4N4O +N2 +H2O.
Adenine Hypoxanthine
Similar transformation, where xanthine and hypoxanthine are pro-
duced secondarily, may also occur in the hydrolysis of nucleic acids as
well as in putrefaction and by the action of special enzymes. The
researches of Schittenhelm, Levene, Jones, Partridge, Winternitz,
and Burian have shown that in various organs deamination enzymes,
such as guanase and adenase, occur, which convert guanine and adenine
into xanthine and hypoxanthine respectively, and also oxidases which
oxidize hypoxanthine into xanthine and this then into uric acid. This
formation of uric acid from the purine bases, which will be discussed in
detail in a following chapter (XIV), is of very great interest.
The nuclein bases form crystalline salts with mineral acids, which,
with the exception of the adenine salts, are decomposed by water. They
are easily dissolved by alkalies, while with ammonia their action is some-
what different. They are all precipitated from acid solution by phos-
photungstic acid; they also separate as silver compounds on addition
of ammonia and ammoniacal silver-nitrate solution. These precipitates
are soluble in boiling nitric acid of 1.1 specific gravity. All purine bodies
are also precipitated by Fehling’s solution (see Chapter III) in the pres-
ence of a reducing substance such as hydroxylamine (Drechsel and
Balke). Copper sulphate and sodium bisulphite may also be used to
1
Zeitschr. f. physiol. Chem.. 7.
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