G. ROBERT GREENBERG 



LITERATURE 



It is common experience that one of the best training grounds 

 for the investigation of multi-enzyme systems is a thorough study 

 of glycolysis. All of the necessary tools, concepts, and difficulties 

 can be found in these studies which span 50 years. Unfor- 

 tunately although many of the concepts involved now have 

 emerged in a relatively simple form they tend not to become 

 part of one's armamentarium until some aspects of the scheme 

 have actually been studied. 



Dixon (7) has written an excellent little book on the prob- 

 lems of multi-enzyme systems, and this may be recommended as 

 a source of stimulation and of orientation. He has considered 

 the problems arising in the study of glycolysis, such as coupled 

 systems, competing enzyme systems, limiting reactions, equilib- 

 ria, and the role of K^. Green (11) has dealt with enzymes in 

 sequence and has considered many aspects of the organization of 

 enzyme systems. Although many of the newer texts have 

 well-developed chapters on the characteristics of enzymes, little 

 space is devoted to multi-enzyme studies, understandably so be- 

 cause of the qualitative nature of the problem. However, the 

 discussions by Fruton and Simmonds (8) are especially helpful. 



Some Approaches to Multi-Enzyme Systems (MES) * 



THE BALANCE 



Given a particular pathway to study and knowing the be- 

 ginning substrates, the student is faced with the problem of 

 obtaining intermediates while fractionating somewhat blindly, 

 assaying for the disappearance of a substrate and the appearance 

 of the product. This approach certainly has yielded important 



* Abbreviations : MES, multi-enzyme system; AMP, adenosine-5'- 

 phosphate; IMP, inosine-5 '-phosphate; IRMP, 5-amino-4-imidazoIecarbox- 

 amide-5 '-phosphoriboside ; HX, hypoxanthine ; R-5-P, ribose-5-phosphate; 

 R-l-P, ribose-1 -phosphate; PRA, 5-phosphoribosylamine ; FAH4, tetrahydro- 

 folic acid; N10-CHOFAH4, Nio-formyl derivative of FAH4; PRPP, 5-phospho- 

 ribosylpyrophosphate. 



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