ENZYMIC DEGRADATION AND BIOSYNTHESIS 



73 



HC- 



OH 



I 

 ■C — 



I I 

 1 H 



0=C^ CH 



OH 



I 

 -C — C— CH9O- 



I I 



H H 



COCHo 



I ' 



^r^/ 



CH 



NH 



I 



C— C— 

 H H 



L-ala 



OH 

 I 



-C— C 

 H H 



-CH, 



-CHoOH 



OH 



D-glu 



I 

 L-lys 



I 

 D-ala 



I 

 D-ala 



COO" 



Fig. 16. Structure of the uridine nucleotide from penicillin-inhibited 

 Staphylococcus aureus.^o 



on bacteria (including the Gram-negative Escherichia coli) 

 by blocking wall formation. Thus the biochemical and 

 structural evidence for the inhibition of wall formation by 

 penicillin emerged and has been largely confirmed in many 

 subsequent studies. The anatomical lesion caused by peni- 

 cillin inhibition of wall formation is beautifully illustrated 

 in the thin sections of Staphylococcus aureus shown in Fig. 

 17a and b, taken from the studies of Murray, Francombe, 

 and Mayall.^^ The consequences of inhibition of the for- 

 mation of the mucopeptide part of the wall of Gram-nega- 

 tive bacteria has become apparent from a number of inves- 

 tigations. ^^^^^^ However, the Gram-negative bacteria have 

 major wall constituents unaffected by penicillin action, and 

 the familiar "poached-egg" appearance of "protoplasts" of 

 Vibrio metchnikovi formed in the presence of penicillin is 

 shown in Fig. 17c. 



