78 MICROBIAL CELL WALLS 



TABLE 24 



Antagonism by D-alanine of Uridine Nucleotide Accumulation 

 Induced by Oxamycin 



Antagonist Added Experiment 1 Experiment 2 



In Experiment 1 oxamycin (75 ^g/nil) and possible antagonists 

 were added together at time. In Experiment 2 oxamycin (75 

 /Ag/ml) was added at time. At 45 minutes, 20.4 ^M of nucleotide 

 had accumulated. At this time possible antagonists were added 

 and incubation was continued for 45 minutes longer. Data are 

 expressed as /xmoles of uridine nucleotide per liter of culture at 

 half-maximal growth. 



Reference 63. 



acid composition to that of the cell-wall mucopeptide ^^ and 

 even very close agreement in the proportions of the d- and 

 L-alanine,*^^ as shown in Table 25. Of course, an alternative 

 explanation of the presence of glycine in a "special" peptide 

 or structure would equally well explain its absence from 

 the nucleotides. 



Enzyrjiic Synthesis of Wall-Precursor Nucleotides. Con- 

 ditions leading to the formation of a uridine nucleotide 

 have been investigated for only one of the cell-wall inter- 

 mediates. Ito and Strominger "'^ have found that an en- 

 zyme from Staphylococcus aureus purified about 500-fold, 

 will catalyze the formation of UDP-AG-lact-ala-glu-lys under 

 the conditions summarized in Table 26. 



