The nature of enzyme action / by W. M. Bayliss.

  • Bayliss, William Maddock, Sir, 1860-1924.
Date:
1914
Catalogue details

Licence: In copyright

Credit: The nature of enzyme action / by W. M. Bayliss. Source: Wellcome Collection.

    153/196 (page 141)
    to remind the reader, when one substance is reduced another is at the same time oxidised. The difference in the two cases before us is in the means by which the reaction is brought about, whether it is effected by the activation of oxygen or of hydrogen. In this con- nection, the work of Bredig and Sommer [1910] on the action of colloidal platinum as a reducing catalyst and the relation of the phenomena to the coupled reactions, to be described in the following section of this chapter, may be consulted with advantage. Coupled Reactions. There is an interesting class of chemical reactions called by Ostwald [1900] “coupled reactions,” which it seems probable will have to be taken into account in oxidation, and perhaps also in other pro- cesses in the organism. An instance of such a reaction is the follow- ing : When a solution of sodium arsenite is shaken with air no oxidation takes place ; sodium sulphite similarly treated is rapidly oxidised; if a mixture of the two be shaken with air both salts are oxidised. In some way or other oxygen is activated in the process. It is convenient to give names to reactions in which a slow reaction is accelerated by the existence of a simultaneous rapid reaction be- tween one of the reacting bodies of the former reaction and a third body. The rapid reaction is called the “ primary reaction,” and that which is induced by the presence of the former is called the “ second- ary reaction ”. The body common to both is called the “ actor ” ; the second substance in the primary reaction is the “ inductor ” ; and the corresponding body in the secondary reaction is the “ acceptor ”. In the example given, oxygen is the actor, sodium sulphite the inductor, and sodium arsenite the acceptor. Certain catalytic re- actions already referred to may be described from this point of view; the catalysis by ferrous sulphate of the oxidation of hydriodic acid by hydrogen peroxide is one of these. In this process, the reaction FeSO^ -f- H2O2 is the primary reaction, HgOg + HI is the secondary reaction, H2O2 is the actor, FeSO^ the inductor, and HI is the ac- ceptor. For further information on this question, as yet imperfectly worked out, the reader is referred to Mellor’s Chemical Statics and Dynamics.