152 PHYSIOLOGY OF NUTRITION 



According to the theory of Bach and Chodat' the oxidases are not to be con- 

 sidered as simple substances; they consist of peroxidases (oxidizing enzymes) 

 and oxygenases (organic peroxides). Frequently the blue color with tincture 

 of gum guaiac appears only after addition of hydrogen peroxide, in which cases 

 it is evident that only peroxydase is present; hydrogen peroxide here takes the 

 place of oxygenases, which are absent. 



E. Buchner and his co-workers^ have isolated an enzyme from yeast, which 

 splits glucose into ethyl alcohol and carbon dioxide, the so-called zymase. If 

 compressed yeast is' triturated in water with quartz sand and infusorial earth 

 (kieselguhr), and is then subjected to high pressure with a hydrauUc press, a 

 hquid is obtained that is free from cells, and that produces a very active alcoholic 

 fermentation. For example, from 26 g. of glucose were obtained 12.4 g. of 

 alcohol and 12.2 g. of carbon dioxide. Thus, as the theory demands, almost 

 equal amounts of alcohol and of carbon dioxide are produced; 160 g. CeH^Oe 

 = 92 g. CjHeO -I- 88 g. CO2. 



Zymase has also been isolated' by treating yeast with acetone. The yeast 

 is first pressed to remove most of the water and is then placed in a sieve and 

 plunged in a flat dish of acetone for ten minutes. The material is then pressed 

 again, treated with acetone and washed with ether, after which it is pulverized 

 and dried (beginning at room temperature and ending at 65°C.). This prepara- 

 tion, which possesses keeping-qualities, is on the market under the name of 

 zymin.^ In sugar solutions it produces alcoholic fermentation. Lebedev^ 

 gives a good method for obtaining a very active enzyme from thoroughly 

 macerated dry yeast. * 



More extended researches' upon alcohoHc fermentation have shown that 

 zymase, like diastase, is not a single enzyme.'' It is supposed that glucose is 

 split up by dextrase into two molecules of dihydroxyacetone, CH2OH — CO — 



1 Bach, A., and Chodat, R., Zerlegung der sogennanten Oxydasen in Oxygenasen und Peroxygenasen 

 Ber. Deutsch. Chem. Ges. 36: 606-609. 1904. Chodat R., and Bach, A., Recherches sur les ferments oxy- 

 dants. Arch. sci. phys. et nat. IV, 17: 477-Sio. 1904. Idem, Untersuchungen liber die RoUe der 

 Peroxyde in der Chemie der lebenden Zelle. VII. Einiges iiber die chemische Natur der oxydasen. 

 Ber. Deutsch. Chem. Ges. 37^: 36-43. 1904. Idem, same title. VIII. Ueber die Wirkungsweise der 

 Peroxydase. Ibid. 37" : 1342-1348. 1904. Engler, C, and Weissberg, J., Kritische Studien iiber die 

 Vorgange der Autoxydation. 204 p. Braunschweig, 1904. Haar, A. W. van der, Untersuchungen iiber 

 Pflanzen-Peroxydasen. I. Eine neue Methode der Peroxydasen-Gewinnung. Ibid. 43": 1321-1327. 

 1910. Idem, same title. II. Die Hedera-Peroxydase, ein Glucoproteid. Jdid. 43'-': 1327-1329. 1910. 

 Bach, A., Die langsame Verbrennung und die Oxydationsfermente. Fortschr. naturw. Forsch. i : 85-140! 

 1910. Palladine, W., und Iraklionoff, P., La peroxydase et les pigments respiratoires chez les plantes. 

 Rev. gSn.bot. 23:225-247. 1911. [For more recent literature see Atkins, 1916. [See note o, p. 115.] J 



2 Buchner, ■ Eduard, Buchner, Hans, and Hahn, Martin, Die ZymasegSrung, Untersuchungen uber 

 den Inhalt der Hefezellen und die biologische Seite des Garungsproblems. Munchen and Berlin, 1903. 



' Albert, R., Buchner, E., and Rapp, R., Herstellung von Dauerhefe mittels Aceton. Ber. Deutsch. 

 Chem. Ges. 35 : 2376-2382. 1902. 



• It may be obtained from A. Schroder, Munchen, Landwehrstrasse 45. 



'Lebedew, A., Darstellung des aktiven Hetensaftes duvch Maceration. Zeitsch. physiol. Chem. 73: 

 447-452. 1911. 



• This is also to be obtained from Schroder, as " Trocken-Hefe nach A. Lebedew." 



' Jensen, P. Boysen, Die Zersetzung des Zuckers w&hrend des Respirationsprozesses. Ber. Deutsch. 

 Bot. Ges. 26a: 666-667. 1908. Idem, Sokkersonderdelingen under respirationsprocessen hos hdjere 

 planter. Kjobenhavn, 1910.* Buchner, Edward, and Meisenheimer, Jakob, Die chemischen VorgSnge 

 bei der alkoholischen Garung. (IV. Mdtteilung.) Ber. Deutsch. Chem. Ges. 43": 1773-1795. 1910. 



• This paragraph is omitted in the 7th Russian edition.— £d. 



