THE ROLE OF NUCLEOXmES AND COENZYMES 

 IN ENZYMATIC PROCESSES 



FRANK M. HUENNEKENS, Department of Biochemistry, University of 



Washington, Seattle, Washington 



Introduction 



During the past thirty-five years the field of enzyme chem- 

 istry has evolved from a tiny island in the realm of biochemistry 

 to such vast and heroic proportions that it now begins to over- 

 whelm the field itself by virtue of its almost universal applica- 

 bility. Some idea of the accelerated pace in enzymology can be 

 gained from the fact that it required a number of years in the 

 1930's before Warburg completed his classical studies showing 

 that the oxidation of glucose-6-phosphate was mediated by the 

 concerted action of four highly purified components, two pro- 

 teins, a dehydrogenase and an electron carrier, and two co- 

 enzymes, TPN and FMN.* Today the isolation and description 

 of a new enzyme system, perhaps with its attendant coenzyme, 

 is greeted with far less amazement, simply because such events 

 have become commonplace. This casual attitude is not wholly 

 unexpected, since, as the history of science so eloquently shows, it 



* The following abbreviations will be used : DPN, TPN, di- and tri- 

 phosphopyridine nucleotides; FMN, riboflavin-5 '-phosphate; FAD, flavin 

 adenine dinucleotide; CoA, coenzyme A; AMP, ADP, ATP, adenosine mono-, 

 di-, and tri-phosphate; P, inorganic phosphate; PP, pyrophosphate; UDPG, 

 uridine diphosphate glucose. 



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