DISCUSSION ON ANIMAL TISSUE RESPIRATION 



279 



starting the oxidative pathway through Szent-Gyorgyi's cycle, or it 

 may produce phosphopyruvic acid and thus start the synthesis of 

 carbohydrate. These manifold reactions of pyruvate, all of them 

 present in different degrees in animal tissues, show that the orienta- 

 tion of reactions during the metabolism of carbohydrates is ex- 

 tremely complex, and certainly diflFerent from tissue to tissue. 



^, oxidation 

 Glucose > 



,^ II 1 , . oxidation 

 Hexose monophosphate 



it 

 Hexose diphosphate 



it 

 Phosphoglyceraldehyde + Py (PO4) 2 



it 

 Phosphoglycerate + Py (PO4) 2H2 



it t I 



Phosphopyruvate < 



Py(P04)2H2 i 

 Lactate ^^ Pyruvate 



oxidation 



Diphosphothiamine-proteins 



O 



4- '■ *^ - 



>> c3 



-a 



is ^ 







9, 03 



S 4> H 



^ ."S o a 



< ^■ 



Malate 



Fumarate 



Succinate 



Fe^"*"*" cytochrome c 



Cytochrome oxidase 



IT 

 o. 



