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REDUCTION PROCESSES. 877
of sulphur to H2S and others, can be brought about by the labile H of the
Bulphydryl-compounds. In this manner for example the cysteine
(see Chapter II) arts and quickly reacts with sulphur with the formation
of H2S and similarly acting substances have been detected by IIkffter
in various organs and organ extracts. We have here a group of reductions
which are not of an enzyme nature.
From the investigations of Abelous and Aloy l
it follows that
plants as well as animal organs have the ability at the same time of oxidiz-
ing salicylaldehyde and of reducing nitrates to nitrites. On the other
hand ScHARDiNGEit, Trommsdorff and Bach 2
have shown that fresh
cow’s milk, which alone is without action upon methylene blue and on
nitrates, reduces these bodies in the presence of aldehydes into leucobases
or nitrites. Boiled milk does not have this power and the action is
explained by the presence of a reductase, the so-called Schardinger
enzyme. The optimum of action lies at about 70° C. Bach found the same
action in various animal organs. The process may to be just as well
considered as an oxidation under the influence of an aldehydase whereby
the methylene blue or the nitrate gives up the oxygen for the oxidation
of the aldehyde. On the other hand Strassner 3
ascribes the reduction
of the methylene blue to the above-mentioned reducing action of the
sulphydryl groups.
1
Compt. Rend., 138, 382 (1904); see also Pozzi-Escot, ibid., 13S, 511.
2
Schardinger, Zeitschr. f. Unters. d. Nahrune;s- und Genussmittel, 5, 22 (1902);
Trommsdorff, Centralbl. f. Bakter., 49, 291 (1909); Bach, Ber. d. d. chem. Gesellsch.,
42. 4463 (1909); Bioch. Zeitschr., 31, 443; 33, 2S2; 38, 154 (1911).
» Ibid., 29, 295 (1910).
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