HsN 



H OH OH OH 

 I I I I 

 O3POCH0C — C — C — C — C CH2OPO3H 



-ll I I I I 



O OH H H H 



sedoheptulose-l,7-diphosphate 



X p-aminobenzoic acid 



COOH 



unknown 

 intermediate 



HO 



.^^N 



COOH 



HOHk^HOH 



HOH 



shikimic acid 



CH2COCOOH 



^^ COOH 



p-hydroxybenzoic acid 



COOH 



^^^^^ 



anthranilic acid 



HOOC CH9COCOOH 



phenylpyruvic 

 acid 



HOH 

 prephenic acid 



indole 



CH3CHCOO" 



NH3+ 

 alanine 



.^^"^ 



.^^^^ 



CH2CHCOO" 



phenylalanine 



CHoCOCOOH 



CH2CHCOO" 



OH 



p-hydroxyphenyl- 

 pyruvic acid 



serotonin 



^- CH3COC0A 

 acetyl coenzyme A 



CHCOO- 



indoleacetic acid 



CHCOO" 



fumarate 



Tricarboxylic acid 

 cycle 



HOOC(CH2)2COCH2COOH 



/3-ketoadipic acid 



FIGURE 20-2. The inctabolisin of phenylalanine, tyrosine, and tryptophan siinnnar- 

 i/ed Ironi information available in 1959. As customary in the current literature in 

 this area, the acids are written and named in iin-ioni/ed forms. It is probable, of 

 course, that all are ionized to a great extent inside cells. Pairs of arrows signify more 

 than one known step with the reactions concerned omitted here for simplicity. 



467 



