302 



PETER REICHARD 



TABLE X 

 Incorporation of N'*H4C1 into PNA in Liver Slices with and without Addition 



OF NONLABELFD OrOTIC AcID"" 



Lieberman and Kornberg''' have prepared a cell-free extract from an 

 anaerobic bacterium which catalyzed the reactions: 



orotic acid 



DPNH2 



DPN 



I* dihydroorotic acid ;=^ ureidosuccinic acid 



5-acetic acid hydantoin 



The demonstrated reversibility of the first two reactions makes it seem pos- 

 sible that this scheme represents the synthetic reactions by which orotic 

 acid is synthesized by the bacteria (c/. addendum). 



It should be noted that, according to Spicer et al.,^^° Lactobacillus bul- 

 garicus 09 can utilize ureidosuccinic acid but not dihydroorotic acid for 

 growth. ^^"^ 



An attempt to investigate the role of orotic acid as a "natural" intermedi- 

 ate was carried out by Reichard.'"^ Rat liver slices were incubated with N'^- 



129 I. Lieberman and A. Romberg, Federation Proc. 12, 239 (1953). 



130 D. S. Spicer, K. V. Liebert, L. D. Wright, and J. W. Huff, Proc. Soc. Exptl. Med. 

 Biol.lQ, 587 (1952). 



130a This "dihydroorotic acid" was synthesized according to Bachstez and Cavallini 

 [Ber. 66, 681 (1933)]. It has recently been found that this substance is probably 

 not identical with dihj^droorotic acid. When dihydroorotic acid was synthesized 

 by another chemical method or prepared enzymatically according to Lieberman 

 and Kornberg it could replace orotic acid as a growth factor for Lactobacillus 

 bulgaricus 09.'^' Cf. also C. S. Miller, J. T. Gordon, and E. L. Engelhardt, /. Atn . 

 Chem. Soc. 75, 6086 (1953). 



