The oxidases and other oxygen - catalysts concerned in biological oxidations / by J. H. Kastle.

  • Kastle, Joseph H. (Joseph Hoeing), 1864-1916.
Date:
[1910]
Catalogue details

Licence: In copyright

Credit: The oxidases and other oxygen - catalysts concerned in biological oxidations / by J. H. Kastle. Source: Wellcome Collection.

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    Chapter II. THE OXIDIZING FERMENTS. In its present shape, therefore, the peroxide theory of oxidation accounts for the phenomena of autoxidation and oxygen carrying upon the supposition that spontaneously oxidizable substances have the power of combining with partially dissociated molecules of oxygen to form peroxides. These peroxides may then react either with addi- tional amounts of the autoxidizable substance itself or with some other substance to form simpler oxides. Thus, it may happen that as the result of its oxidation one substance, A, may effect the oxidation of a second substance, B, which latter is not directly oxidizable under ordinary conditions. In this way the modern theory' of oxidation affords a simple explanation of the formation of peroxides and of the phenomenon of oxygen carrying. The numerous applications of this theory are by no means confined to the inorganic world. In the life cycle of the plant and animal we meet with many changes which, in so far as oxygen is involved, find their simplest explanation in terms of this hypothesis. The affinity for oxygen which is displayed not only by the warm-blooded animals, but even by plants, is often remarkable. That such is the case may be gathered from the fact that Phipson (32°) in 1896 employed one of the higher fungi, Agaricus atramentarius, as an agent wherewith to effect the analysis of atmospheric air. It has so happened, therefore, that in the history of our science both a mouse and a mushroom have been employed as oxygen absorbents wherewith to determine the quantity of oxj'gen in atmospheric air. During the absorption of oxygen by plants various substances are produced which are capable of effecting oxidations which ordinarily can not be brought about by molecular oxygen alone, such, for example, as the bluing of guaiacum, the conversion of hydroquinone into quinone, the liberation of iodine from potassium iodide, etc. Like many of the chemical agents of the living cell, these powerful oxidizing substances are characterized by great instability. They are destroyed by heat and mineral acids and by various poisons, such as hydrogen cyanide, sulphur dioxide, phe- nylhydrazin, etc. It is claimed by some observers that they act catalytically, and hence are believed to partake of the nature of fer- ments. These substances are the oxidases,“ or oxidizing ferments, “The following general references to the literature of this subject will be found of interest in this connection: Remarques sur les matieres oxydantes, que l’on peut rencontrer chez les etres vivants, by Bourquelot (M); Ueber Oxydationsfermente, by