CHEMICAL PROPERTIES 



423 



on enzymes was by Quastel (1933 b) on urease and by Bersin and Logemann 

 (1933) on papain. Metabolic studies were largely ignored until 10 years 

 later and quantitative and thorough investigations on respiration, glycoly- 

 sis, the cycle, and other important pathways of metabolism are relatively 

 uncommon even today.* 



The term quinones will refer generically to all the quinones whatever 

 the number of rings or the substituents, diphenol will designate any aromatic 

 compound with two hydroxy groups, and polyphenol any aromatic com- 

 pound with two or more hydroxy groups on the rings. The system of ab- 

 breviations to be used in the tables is summarized in the following tabu- 

 lation. 



CHEMICAL PROPERTIES 



Some of the quinones most commonly used in inhibition studies are shown 

 in jbhe accompanying formulas (other naturally occurring quinones are 

 m on pages 471, 543). 



* Although it is difficult, and perhaps artificial, to separate the groups of quinones 

 for special discussion, the antimalarial naphthoquinones typified by SN-5949, which 

 potently block electron transport at specific sites, will not be treated in this chapter 

 but will be discussed in a future volume with antimycin A and other inhibitors having 

 similar actions. 



