284 ENZYMES 



tion reactions of anaerobic glycolysis (Chap. 13) proceed through DPN- 

 linked enzymes only. 



REVIEW QUESTIONS ON ENZYMES 



1. Explain the terms (1) apoenzyme, (2) coenzyme, (3) zymogen, (4) activator, 

 (5) carrier. 



2. How general is the occurrence of enzymes in nature? Distinguish between endo- 

 and exo-enzymes. 



3. (1) Name five of the enzymes that have been obtained in the crystalline state. 

 (2) What has proved to be the chemical nature of all crystallized enzymes? 



4. (1) What is the essential nature of enzyme action? (2) What is the effect of 

 an enzyme on the chemical equilibrium of a reaction? 



5. (1) List the factors that influence the rate of enzyme action and discuss eacli 

 briefly. (2) What is meant by specificity of enzymes? 



6. What is probably the mechanism of enzyme action? 



7. Define the following: (1) dehydrogenase, (2) catalase, (3) oxidase, (4) peroxidase. 



8. What is the cliemical nature of the cytochromes, and to what substance previ- 

 ously studied are they therefore related? 



9. Explain wherein the structure of (1) glutathione, (2) DPN, (3) riboflavin phos- 

 phate, and (4) cytochrome c could make it possible for these compounds to function 

 in tissue oxidation. 



REFERENCES AND SUGGESTED READINGS 



Baldwin, E., Dynamic Aspects of Biochemistry, 2nd ed., Cambridge University Press, 



Cambridge, 1952. 

 Baddiley, J. and Thain, E. M., "Coenzyme A. Part III. Synthesis of Pantothenic 



Acid-2':4' Phosphate and Further Structural Considerations," J. Chem. Sac, 3421 



(1951). 

 Caputto, R., Leloir, L. F., Trucco, R. E., Cardini, C. E., and Paladini, A. C, /. Biol. 



Chem., 179,497 (1949). 

 Haldane, J. B. S., Enzymes, Longmans, Green and Company, New York, 1930. 

 Lardy, H. A. (editor) Respiratory Enzymes, Burgess Publishing Company, Min- 

 neapolis, 1949. 

 Lardy, H. A., "Vitamins and Carbohydi-ate Metabolism," J. Chem. Ed., 25, 262 (1948). 

 Lipmann, F., Kaplan, N. 0., Novelli, G. D., Tuttle, L. C, and Guirard, B. M., 



"Coenzyme for Acetylation, a Pantothenic Acid Derivative," J. Biol. Chem., 167, 



869 (1947). 

 McElroy, W. D. and Glass, B., Phosphorus Metabolism, Vol. I, The Johns Hopkins 



Press, Baltimore, 1951. 

 Northrop, J. H., Kunitz, M., and Herriot, R. M., Crystalline Enzymes, Columbia 



University Press, New York, 1948. 

 Peters, R. A. and Thompson, R. H. S., "Pyruvic Acid as an Intermediary Metabolite 



in the Brain Tissue of Avitaminous and Normal Pigeons," Biochem. J., 28, 916 



(1934). 

 Sumner, J. B. and Myrback, K., Tlie Enzymes, Academic Press Inc., New York, 1951. 

 Thunberg, T., "Action of Animal Tissues on Methylene Blue," Skand. Arch. Physiol., 



35, 163 (1917). 

 Velick, S. F. and Ronzoni, E., "The Amino Acid Composition of Aldolase and 



D-Glyceraldehyde Phosphate Dehydrogenase," J. Biol. Chem., 173, 627 (1948). 



