232 BIOCHIMICA ET BIOPHYSICA ACTA VOL. 4 (1950) 



THE BIOLOGICAL INCORPORATION OF 



PURINES AND PYRIMIDINES INTO NUCLEOSIDES 



AND NUCLEIC ACID 



by 



HERMAN M. KALCKAR 

 Enzyme Research Division, University of Copenhagen (Denmark) 



INTRODUCTION 



The fundamental studies by Meyerhof and his associates on the metaboHsm of 

 phosphoric esters in muscle extracts marked the beginning of a very fruitful era in 

 which the pathway of breakdown and synthesis of carbohydrates gradually became 

 known. Meyerhof showed that Harden and Young's discovery of phosphate uptake 

 in cell-free yeast fermentation mixtures could be extended to animal tissues, especially 

 muscle. Later Meyerhof and his associates and Needham and Pillai in Cambridge 

 showed that esterification of phosphate in muscle was coupled to the oxidation-reduction 

 between phosphotriose and cozymase. This development led to the discovery of the 

 acylphosphates (Warburg and coworkers, Lipmann). It was known, however, from 

 Lundsgaard's studies that muscle, performing alactacid contractions in an oxygen-free 

 atmosphere accumulates large amounts of hexosephosphoric esters. This is further 

 accentuated if dinitrophenol which 'uncouples' oxidati^e-reductive phosphorylation is 

 added together with iodoacetate. These observations which were made by Cori and 

 CoRi in 1936 indicated that phosphate can also be incorporated into ester linkage by 

 another process which has nothing to do with oxidation-reduction. The phenomenon 

 of phosphate uptake independent of oxidation-reduction was very soon encountered in 

 in vitro experiments too. Within the same year Parnas and Ostern reported that the 

 glycogen present in aged and dialysed muscle extracts canreact with inorganic phosphate. 

 A few months later Carl and Gerty Cori isolated a-glucose-1-phosphate from muscle 

 extracts and three years later CoRi, Cori, and Schmidt demonstrated the synthesis of 

 a polysaccharide from a-glucose-1-phosphate by means of a muscle enzyme. Kiessling, 

 a student of Meyerhof, performed independently in 1939 an analogous in vitro syn- 

 thesis of polysaccharide using a yeast enzyme. During the subsequent years Cori and 

 his associates turned their attention towards the kinetics of starch and glycogen synthe- 

 sis in vitro. A number of important studies on starch, dextran and sucrose formation in 

 enzyme systems from plants and microorganisms appeared during the next three or 

 four years. The studies on the enzymatic synthesis of ribo- and desoxyribonucleosides 

 can also be considered an outgrowth of Cori's fundamental observ^ations on phospho- 

 rolysis of glucosidic linkages. 

 References p. 22y. 



