60 METABOLIC PATHWAYS IN MICROORGANISMS 



Ag = per cent total C^^02 yields from systems metabo- 

 lizing equal amounts of gluconate labeled in these 

 positions 



Gp = fraction of the administered glucose catabolized 

 via phosphogluconate cleavage 



In equation 2 a correction factor has been introduced 

 into the term Gq (equation 1). The coiTection arises from 

 the understanding that the term Gq in reality represents 

 a total conversion of C-6 of glucose to CO2 via both glycoly- 

 sis and the pentose cycle pathways, whereas the derivation 

 of equation 1 calls for the consideration of CO2 produc- 

 tion from C-6 of glucose via the glycolysis exclusively. The 

 COo production from C-6 of glucose via the pentose cycle 

 reactions can be represented as Aq{Gp) since G^ represents 

 the fraction of glucose routed into the pentose cycle and Aq 

 represents the CO2 yield from C-6 of glucose by way of 

 phosphogluconate. Consequently, the term (Gq-AqGp) rep- 

 resents the net production of CO2 from C-6 of glucose via 

 the glycolysis-Krebs cycle pathway which is theoretically 

 identical to the production of CO2 from C-1 of glucose via 

 the same metabolic route. 



When equation 2 is used in place of equation 1 to cal- 

 culate the pathway participation in B. suhtilis, the previous 

 value of 26% for phosphogluconate decarboxylation rises to 

 41%. Similar refinements (including a determination of 

 gluconate conversion to COo) are in progress with several 

 other organisms. Table 2.4 lists several organisms in which 

 the extent of participating pathways is reasonably well 

 known, although several may be revised when adequate 

 values for gluconate oxidation are available. 



Knowledge of catabolism of glucose via catabolic path- 

 ways in animals is in a less satisfactory state, although in 



