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

  • Joseph Hoeing Kastle
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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    a blue coloration with potassium iodide and starch, but no reaction with titanic acid. Nitrites were also shown to be absent. Hence accoiding to these authors, the separation of the iodine from the potassium iodide could only have been brought about by an acyl- hydroperoxide. A similar experiment carried out on a specimen of the Lathrsea squamaria sap which had lost its power to blue guai- acum gave a completely negative result. Hence the peroxide forma- ■ tion with the active sap depends on the presence of the oxidase, and leads to the belief that the oxidase itself is, of a peroxide nature, or that it at least contains a peroxide as one of its constituents. Schoenbein, in his paper on the catalytic action of organic materials (peroxidases and catalases) and their distribution in the plant and animal kingdoms (383), explains the activating and catalyzing power of such substances on the supposition that, like lead acetate, they ] convert hydrogen peroxide (an antozonide) into an ozonide (like lead peroxide), and that under the influence of the latter the former is actively decomposed with the production of water and molecular \ oxygen. Thus he proved that when lead acetate is added to a solution of hydrogen peroxide, lead peroxide (an ozonide) is formed, under the influence of which the hydrogen peroxide is actively decomposed; and that if lead acetate be added to hydrogen peroxide solution con- taining guaiacum, the latter is oxidized at the same time that a part of the hydrogen peroxide is decomposed, for the reason that the lead ; peroxide oxidizes the guaiacum at the same time that it decomposes! the hydrogen peroxide. According to Schoenbein, therefore, what we now know as the peroxidases are those substances occurring in the secretions and tissues of animals and plants which have the power of ozonizing hydrogen peroxide or converting it into an ozonide. The catalysis or decomposition of the hydrogen peroxide he looked upon as a secondary phenomenon resulting from the action of the ozonide thus formed upon the hydrogen peroxide remaining unchanged. Lepinois (203) conceives that the decomposition of hydrogen peroxide takes place in such a way that where only a part of the oxygen is set free it is fixed by the guaiacum or guaiacol. From their study of the hydrogen peroxide-guaiacum reaction, Kastle and Loevenliart (2U) arrived at the conclusion that the per- oxidases are substances which are capable of reacting with hydro- gen peroxide to form peroxides, which are more vigorous oxidizing agents than hydrogen peroxide itself. This view regarding the nature of these substances has been concurred in by Bach(20). The decomposition of hydrogen peroxide and the mechanism of oxida-;: tions by means of this substance has formed the subject of a still further investigation by Loevenliart and Kastle (275). It is now known that hydrogen peroxide undergoes spontaneous decomposi- tion into water and molecular oxygen; it is also known that it can