PROTEIN METABOLISM 

 Pyruvate ■ 



'OOCCHgCHCOO 



oxalacetate 



citrate 



465 

 CH3CHCOO- 

 NH3+ 



alanine 



Tricarboxylic 

 acid cycle 



c/s-aconitate 



isocitrate 



/ 



succinate oxalsuccinate 



a - ketoglutarate 



citrulline 



H2NCONH2 

 urea 



"OOC(CH2)9CHCOO" 



NH3+ 

 glutamate 



OHC(CH2)2CHCOO- 



NH3+ 



glutamic semialdehyde 



'^. 



N" 



JCOOH 



0P03H- 



carbamyl 

 phosphate 



A'-pyrroline-5- 

 carboxylic acid 



H2 



proline 



HOH 



HCOO- 



+ 

 H. 



HCOO" 



hydroxyproline 



FIGURE 20-1. Metabolic transformations as of 1959 for several amino acids connected 

 directly with the tricarboxylic acid cycle. Arrows with points on both ends signify 

 demonstrated reversibility, while reactions represented by arrows with one pointed 



end are not known to be reversible. 



