62 PHYSIOLOGY OF THE FUNGI 



waste energy in the form of heat which is not iitihzed by the fungi. The 

 efficiency of utiHzation depends upon the substrate utihzcd and upon the 

 nature of the coupled reactions. In any case only a part of the energy 

 available in the sulDstrate does useful chemical work for the fungus utiliz- 

 ing it. The application of these ideas with any rigor requires a sound 

 knowledge of thermodynamics. 



SUMMARY 



The chemical reactions which underlie the life processes of fungi and 

 other organisms are initiated by organic catalysts, or enzymes. Enzymes 

 catalyze synthetic as well as degradation reactions and are mediators of 

 energy transfer as well. 



Enzymes are specific proteins which in some instances require certain 

 metallic ions or organic coenzymes, or both, before they are active. In 

 general, an enzyme controls but a single type of reaction. In living 

 organisms these enzyme-controlled reactions are correlated and integrated 

 to a high degree. 



Among the external factors which modify the action of enzymes the 

 following are especially important: temperature, hydrogen-ion concentra- 

 tion, concentration of substrate and products, and inhibitors. The 

 effects of these factors on isolated enzymes and intact organisms are much 

 the same. 



While the role of enzymes in maintaining life processes in fungi and 

 other organisms is well established, the application of this information to 

 living fungi must be made with due caution and the realization that a 

 living organism is more complex than its parts. 



REFERENCES 



Barron, E. S. G., S. Dickman, and T. P. Singer: On the inhibition ol enzymes by 



ionizing radiations, Fed. Proc. 6 : 236, 1947. 

 *Bayliss, W. M.: The Nature of Enzyme Action, 2d ed., Longmans, Roberts and 



Green, London, 1925. 

 Bergmann, M.: A classification of proteolytic enzymes. Advances in Enzymol. 2: 



49-68, 1942. 

 Bonner, J.: The chemistry and physiology of the pectins, Botan. Rev. 2: 475-497, 



1936. 

 Bourqxtelot, E.: La Synthese biochimique des d-glucosides d'alcools monovalents. 



II. AlcooW-glucosides a, Ann. chim., Ser. IX, 3: 287-337, 1915. 

 Buchner, E.: Alcoholische Garung ohne Hefezellen, Ber. d. deut. chem. Ges. 30: 



117-124, 1897. 

 BtJNNiNG, E.: Ueber die Farbstoff- und Nitrataufnahme bei Aspergillus niger, Flora 



131:87-112, 1936. 

 Coryell, C. D.: The proposed terms "exergonic" and "endergonic" for thermo- 

 dynamics. Science 92 : 380, 1940. 

 DrxoN, M.: Multi-enzyme Systems, Cambridge University Press, New York, 1949. 

 Elvehjem, C. a., and P. W. Wilson (Editors): Respiratory Enzymes, Burgess 



Publishing Co., Minneapolis, 1944. 



