102 B. L. HORECKER, P. Z. SMYRNIOTIS VOL. 12 (ig53) 



physiological significance, it becomes necessary to postulate the presence in intact cells 

 of a lactonization enzyme which catalyzes reaction^. 



We are indebted to Dr. Fritz Lipmann for suggesting the method of preparation of 

 6-phosphoglucono- S-lactone. 



SUMMARY 



1. The enzymic reduction of 6-phosphoglucono-f5-lactone to glucose-6-phosphate has been ob- 

 tained with reduced TPN and glucose-6-phosphate dehydrogenase, thus demonstrating the revers- 

 ibiUty of glucose-6-phosphate oxidation. 



2. The half-hfe of 6-phosphoglucono-(5-lactone at pH 7.4 is about 1.5 minutes. 



3. A purified crystalhne preparation of barium gkicose-6-phosphate is described. 



RESUMfi 



1. La 6-phosphoglucono-r5-lactone pent etre reduite enzymatiquement en gkicose-6-phosphate 

 en presence de TPN reduit et de glucose-6-phosphatedeshydrogenase, ce qui montre la reversibihte 

 de I'oxydation du glucose-6-phosphate . 



2. La moitie de la 6-phosphoglucono-(5-lactone est reduite en 1,5 minute environ a pH 7.4. 



3. Une preparation pure cristallisee de gIucose-6-phosphate de baryum est decrite. 



ZUSAMMENFASSUNG 



1. Die enzymatische Reduktion von 6-phosphoglucono-^-lakton zu Glucose-6-phosphat wurde 

 mit reduzierter TPN und Glucose-6-phosphatdehydrogenase erreicht und so die Umkehrbarkeit der 

 Glucose-6-phosphatoxydation gezeigt. 



2. Die Halbwertszeit des 6-Phosphoglucono-^-laktons bei pH 7.4 ist ungefahr 1.5 Minuten. 



3. Ein gereinigtes kristallines Bariumglucose-6-phosphatpraparat wird beschrieben. 



REFERENCES 



1 O. Warburg and W. Christian, Biochem.. Z., z^z (1931) 206; 292 (1937) 287; E. Negelein and 

 E. Haas, Biochem. Z., 282 (1935) 206. 



2 O. Warburg, W. Christian and A. Griese, Biochem. Z., 282, (1935) 157. 

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* B. L. Horecker and P. Z. Smyrniotis, /. Biol. Chem., 196 (1952) 135. 



^ O. Cori and F. Lipmann, /. Biol. Chem., 194 (1952) 417. 



^ F. Lipmann, in W. D. McElroy and B. Glass, Phosphorous Metabolism, Vol. I, Baltimore, 1951, 

 P. 158. 



^ R. Bentley and a. Neuberger, Biochem. J., 45 (1949) 584. 



** H. J. Strecker and S. Korkes, Nature, 168 (1951) 913. 



^ H. A. Lardy and H. O. L. Fischer, /. Biol. Chem., 164 (i94<') 513. 

 ^° H. S. Isbell, Bur. Standards J . Res., 8 (1932) 615. 

 1^ R. RoBisoN AND E. J. King, Biochem. J., 25 (193 i) 323. 

 ^2 A. Kornberg, /. Biol. Chem., 182 (1950) 805. 



13 B. L. Horecker and P. Z. Smyrniotis, /. Biol. Chem., 193 (1951) 371- 

 " A. Kornberg and B. L. Horecker, Biochemical Prepns., in press. 

 1^ S. OcHOA and E. Weisz-Tabori, J . Biol. Chem., 159 (1945) 245. 

 1* F. Lipmann and L. C. Tuttle, /. Biol. Chem., 159 (1945) 21. 

 1'' S. Hestrin, /. Biol. Chem., 180 (1949) 249. 

 18 W. Vischniac and S. Ochoa, /. Biol. Chem., 195, (1952) 75. 



Received March 27tli, 1953 



3 



