Oxidations and reductions in the animal body / by H.D. Dakin.

  • Dakin, H. D. (Henry Drysdale), 1880-1952
Date:
1912
Catalogue details

Licence: In copyright

Credit: Oxidations and reductions in the animal body / by H.D. Dakin. Source: Wellcome Collection.

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    it was believed that the butyric acid in some way was broken down into smaller molecules which under suitable conditions might undergo synthesis with formation of acetoacetic acid. No chemical analogy was known for the conversion of butyric acid into acetoacetic acid by direct oxidation. It was subsequently found, however, that by a suit- able choice of reagent, namely hydrogen peroxide, this type of reaction could be readily brought about in vitro and it is now generally con- ceded that the same reaction takes place in the animal body. Many additional examples of the results of this type of investigation will be found in succeeding chapters. A third method of obtaining information about intermediate pro- ducts of biochemical oxidation is based upon the following considera- tion. For any particular substance under investigation it is possible to determine by trial the amount which on administration to an animal undergoes practically complete oxidation to its end-products. If in a second experiment a quantity of substance considerably larger than that which can be completely oxidized is administered to the animal, it will be found that in some cases the urine, in addition to unchanged substance, will contain compounds which appear to be intermediate products of oxidation. The possibility of isolating intermediate pro- ducts by this direct method obviously depends upon the relative rates of oxidation of the parent substance and the intermediate products under the particular conditions of the experiment. The necessity of employ- ing large quantities of substance make the conditions of experiment somewhat abnormal and the results must be accepted with some caution. As examples of the method, reference may be made to the forma- tion of intermediate products from /3-phenylpropionic acid (p. 23) to the excretion of oxalic acid by rabbits following large doses of glucose (p. 84) and the isolation of uric acid as an intermediate product in the oxidation of xanthine to allantoine (p. 96). A fourth method of investigation is based upon the study of the action upon oxidizable substances of isolated surviving organs, or of the crushed tissue pulp or cell juices or aqueous extracts of various organs. The investigation of the oxidations which may be effected by the surviving liver when perfused with oxygenated blood has proved specially valuable. Embden’s work on acetoacetic acid formation from fatty acids (p. 21) and Wiechowski’s demonstration of the oxi- dation of uric acid to allantoine (p. 95) are excellent examples ot this method. By the use of isolated organs or organ extracts the tendency of the intact animal to effect complete oxidation of the substance is