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876 RESPIRATION AND OXIDATION.
1. Iodides in acid solution in the presence of H2 2 . According to Bach and
Chodat > this reaction is completely parallel with the guaiac reaction.
2. Formic acid with H2 2 (see above).
3. Amines (especially p-phenyldiamine) which forms colored products on
t aking up oxygen. 2
4. Leucobases or mixtures of their formers, which by oxidation are converted
into pigments. A solution of a mixture of a-naphthol and p-phenylen-diamine
made alkaline with soda gives indophenol on taking up oxygen (Rohmann and
Spitzer 3
).
5. Certain benzene derivatives which on oxidation and loss of water are
transformed into diphenol derivatives, for example vanillin into dehydrodivanillin. 4
For quantitative estimation of the extent of oxidation Bach and Chodat 5
use the transformation of pyrogallol into purpurogallin, which latter can be weighed.
Bach 6
determines the amount of iodine set free in the reaction between hydrogen
peroxide and hydriodic acid and Batelli and Stern 7
determine the quantity of
C02 formed in the oxidation of formic acid.
There is no doubt that reductions occur to a great extent in the animal
body and often go hand in hand with oxidations. The question as to
the extent in which special reduction enzymes are concerned, is still
undecided. As the oxidations are explained by the action of special
enzymes, so also we can admit of special reduction enzymes, so-called
reductases or hydrogenases. To this group belongs the so-called " philo-
thion" (De Rey-Pailhade), which in the presence of sulphur and
water develops sulphuretted hydrogen, while others on the contrary do
not accept this view, and deny the enzyme nature of philothion. 8
The
investigations of Nasse and Rosing 9
on the oxidation of protein in the
presence of sulphur contradict the enzymotic nature of this formation
of sulphuretted hydrogen, and the recent investigations of Heffter 10
have shown that certain reductions occurring in the tissues are not pro-
duced by enzymes. He has also shown that those reductions, which are
not influenced by HCN, like the reduction of pigments (methylene blue),.
1
Ber. d. d. chem. Gesellsch., 35, 2466 (1902).
2
Bioch. Zeitschr., 46, 317 (1912).
» Ber. d. d. chem. Gesellsch., 28, 567 (1894).
* In regard to this and other reagents, see Zeitschr. f. physiol. Chem., 59, 359
(Engler and Herzog).
5
Ber. d. d. chem. Gesellsch., 37, 1342 (1904).
*IUd., 37, 3785 (1904).
7
Bioch. Zeitschr., 31, 443; 33, 282 (1911).
8 De Rey-Pailhade, Recherches exp6r. sur le Philothion, etc., Paris (G. Masson),
1891, and Nouvelles recherches sur le Philothion, Paris (Masson), 1892; Bull. soc.
chim. (4), 1; Pozzi-Escot, Bull. soc. chim. (3), 27, and Chem. Centralbl., 1904, 1,
1645; Chodat and Bach, Ber. d. d. chem. Gesellsch., 36; Abelous and Ribaut, Compt.
Rend., 137, and Bull. soc. chim., (3), 31.
»E. Rosing, Unters. liber die Oxydation von Eiweiss in Gegenwart von Schwefel,
I norg.-Dissert, Rostock, 1891.
10 Med.-naturw. Arch., 1, 81-104; Marburg, cited in Chem. Centralbl., 2, 1907,,
822; Thunberg, Ergebn. d. Physiol., 11.
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