10 PHYSIOLOGICAL CHEMISTRY 



The investigations of Ehrlich 1 and of Neuberg 2 have served to cause 

 a complete revision of our ideas regarding yeast fermentation. Ehrlich, 

 for example, has shown that yeast will liberate ammonia from amino acids 

 and leave behind a non-nitrogenous complex. Among these complexes 

 amyl alcohol, succinic acid and others may be mentioned. Thus, amyl 

 alcohol results from the fermentation of leucine, whereas ethyl alcohol 

 results from the fermentation of sugar. Neuberg has demonstrated the 

 presence in the yeast of an enzyme termed carboxylase which has the 

 property of splitting of carbon dioxide from the carboxyl group of amino 

 and other aliphatic acids. The findings mentioned above constitute the 

 basis for much important work on so-called "sugar-free fermentation." 



For a more extended consideration of enzymes the student is referred 

 to the following sources: 



BAYLISS. The Nature of Enzyme Action, Third Edition, Long- 

 mans, Green and Co., New York and London. 



COHNHEIM. Enzymes, Wiley and Sons, New York, 1912. 



DUCLAUX. Traite de Microbiologie, Masson and Co., Paris. 



EFFRONT. Enzymes and their Applications, Translated by Pres- 

 cott, Wiley and Sons, New York. 



EULER. (a) Allgemeine Chemie der Enzyme, Bergmann, Wies- 

 baden, 1910. (b) Ergebnisse der Physiologic, 1909-10. (c) General 

 Chemistry of the Enzymes, Translated by Pope, Wiley and Sons, 

 1912. 



OPPENHEIMER. Die Fermente und Ihre Wirkungen, Vierte Auflage, 

 Vogel, Leipzig. 



SAMUELY. Handbuch der Biochemie des Menschen und der Thiere 

 (Oppenheimer) , Gustav Fischer, Jena, 1910-11. 



WOHLGEMUTH. Grundriss der Fermentmethoden, 1913, Berlin, 

 Springer. 



EXPERIMENTS ON ENZYMES AND ANTI-ENZYMES 

 A. Experiments on Enzymes 3 



I. AMYLASES 



i. Demonstration of Salivary Amylase. 4 To 25 c.c. of a i per cent starch 

 paste in a small beaker, add 5 drops of saliva and stir thoroughly. At intervals 

 of a minute remove a drop of the solution to one of the depressions of a test-tablet 



1 Ehrlich: Biochemische Zeitschrift, 36, 477, 1911. 



2 Neuberg and Collaborators: Biochemische Zeitschrift, 31, 170; 32, 323; 36 (60, 68, and 

 76), 1911. 



3 If it is deemed advisable by the instructor to give all the practical work upon enzymes 

 at this point in the course, additional experiments will be found in Chapters III, VI, VII, 

 X and XI. 



4 For a discussion of this enzyme see p. 55. 



