256 



H. M. KALCKAR 



VOL. 12 (1953) 



replaced by ribose-i-phosphate (see Addendum, p. 262) but ribose-2-phosphate, ribose-3- 

 phosphate, deoxyribose-i-phosphate and ribose are not active (Table III). 



In contrast to the original extract, the dialyzed preparation incorporates adenine 

 into AMP only. ATP could be shown to react with ribose-i-phosphate. The ATP- 

 dependent enzyme is destroyed by heating at 65° for 5 minutes; preincubation of ribose 

 i-phosphate and ATP with the dialyzed extract, followed by heating at 65°, and then 

 a further incubation with ^^C adenine, yielded ^^C-AMP, but there was not incorporation 

 when the ribose-i-phosphate and ATP were added only after the heating step (Table 

 jyj42_ jjjg enzyme catalyzing the incorporation of adenine into the diphosphoribose is 

 heat stable in contrast to the enzymes which catalyze the formation of the diester. 



TABLE III 



FORMATION OF l'*C-AMP FROM 1*C-ADENINE BY A DIALYZED PIGEON-LIVER EXTRACT 



ctsjmin in yAMP 



Dialyzed extract + -"^^C-adenine 

 Dialyzed extract + "C-adenine + R-5-P + ATP 

 Dialyzed extract + i^C-adenine + R-i-P + ATP 

 Dialyzed extract -f ^^C-adenine + R-2 or 3-P -f ATP 

 Dialyzed extract + "C-adenine + DR-i-P + ATP 

 Dialyzed extract + ^*C-adenine + ribose + ATP 

 Dialyzed extract + ^^C-adenine -f ATP alone 

 Dialyzed extract + ^*C-adenine + R-i-P alone 

 Dialyzed extract + ^*C-adenine + a-G-i, 6-P2 + R-i-P 



+ phosphoglucomutase 

 Dialyzed extract + ^*C-adenine + R-i-P 



+ phosphoglucomutase* 



15 



1868 



2550 

 53 



30 

 90 

 22 



82 

 1840 



iiio 



Spectrophotometric assay showed the presence of G-i, 

 phosphoglucomutase preparation. 



From Saffran and Scarano*-. 



6-P„ in the 



TABLE IV 



preincubation of RIBOSE-MONOPHOSPHATE and ATP 



cts.jmininAMP 



R-I-P 



R-5-P 



Preincubation with ribose-mono- 



phosphate and ATP. 

 Heating at 65° for 5' 



Incubation with ^*C-adenine 

 Heating at 65° for 5' 

 Incubation with ribose-monophos- 



phate, ATP and ^^C-adenine 



1161 



1066 



From Saffran and Scarano*^ 



These observations were very close to a previous one made by the Buchanan group^^ 

 in which they also found an enhancement of inosinic acid formation in pigeon liver by a 

 combined action of ATP and ribose-5-phosphate. The obvious question was whether 

 ATP phosphorylated ribose monophosphate (i or 5-ester) to ribose-i,5-diphosphate. 

 For further pursuit in this direction, Saffran and Scarano were able to benefit from 

 Klenow's demonstration of this ester as the result of an enzymic interaction'*^. It is 

 necessary at this point to add a few remarks about phosphoribomutase. 



References p. 263J264. 



