Pfizer Handbook of Microbial Metabolites 



316 



2 required by valine. The remaining steps of the proposed 

 leucine biosynthesis in microorganisms are; 



CH3 O 



\ II -CO, 



CH— C=0 + CH3— C— COOH -* 



/ I Pyruvic Acid [O] 



CH3 COOH 



a-Ketoisovaleric 

 Acid 



"CHa 



CH3 



CH3 CH3 



\ 



CH — CH2— CH— COOH amination 



/ I < 



CHs 



OH 



I 

 CH— C— CH2— COOH 



' I 



COOH 



CH— CH2— C— COOH*- 



CH3 



NH2 

 Leucine 



a-Ketoisocaproic Acid 



This partial scheme is based on labeled media experiments in 

 yeasts, molds and bacteria. 



The biogenetic scheme of the aromatic amino acids phenyl- 

 alanine and tyrosine was briefly outlined in the introduction to 

 the section on simpler ahcyclic compounds. The final stages 

 of this route are shown here, beginning with shikimic acid: 



COOH Pyruvic Acid 



^> V 



HO 



CH2— CO— COOH 



H — COOH 

 Prephenic Acid 



Shikimic Acid 

 5-Phosphate 



HO 



_ p-Hydroxyphenyllactic Acid 



-CH2— CH— COOH 



CH2— CO— COOH 



Phenylpyruvic Acid 

 kNH3 



f2H 



HO— f V-CH2— CO— COOH ( \-CH2— CH— COOH 



\=/ \=/ I 



p-Hydroxyphenylpyruvic Acid NH2 



l^NHs Phenylalanine 



HO 



i 



CH2— CH— COOH 



NH2 



Tyrosine 



