METABOLIC CYCLES AND DECARBOXYLATION 

 Table 1.— Reactions of pyruvic acid (P.A.) 



199 



Reaction studied 



Tissue used 



P.A. -^ acetaldehyde + CO2 



P.A. + ^02 -^ acetic acid + CO2 



2P.A. + H2O —* lactic acid + acetic acid + CO2 



P.A. + 2H ^ lactic acid 



P.A. + oxalacetic acid — > citric acid 



2P.A. -^ acetic acid + formic acid 



P.A. + glutamic acid — > alanine + a-ketoglutaric acid 



2P.A. — > acetoacetic acid 



2 P.A. —* ^-hydroxybutyric acid 



P.A. — > alanine 



P.A. + acetate — > acetopyruvate — > acetoacetate 



P.A. -tC02 —* a-ketoglutarate 



2P.A. — » acetylmethylcarbinol 



yeast 



brain, gonococcus 



gonococcus, brain, liver 



muscle, tumor 



muscle, liver, kidney 



streptococcus 



muscle 



liver 



muscle 



muscle 



liver 



liver 



muscle 



enzymic channels through which these reactions may flow, and the 

 other with their quantitative capacity to perform the task imposed 

 upon them by their postulated role in the cycle. To the extent that 

 a suspension of minced pigeon breast muscle retains the chemical 

 reactions involved in its respiration in the intact state, the reactions 

 summarized in equation 7 may be regarded as most closely approxi- 



"TRIOSE" 



i -2H- 



PYRUVATE 



OXALACETATE j | +Y^p-2H- 



CITRATE 



cii-ACONlTATE 



ISO-CITRATE 



+ H20-2H- 



o(-KETOGLUTARATE 



i 



J. Pl_l ^ 



frUMARATE 



SUCCINATE 



i 



FUMARATE 

 I H-MALATE 



+ H^0-2H OXALACETATE ' 



U H-MALATE 



-2H-1 



-2H 



-iQ2- 



— ^ 

 ■^H,0 



-2H- 



Figure 1. — Scheme of the oxidative breakdown of carbohydrate 

 in pigeon breast muscle 



