METABOLIC PATHWAYS IN MICROORGANISMS 



H— C=0 



I 

 H— C— OH 



I 

 HO— C— H 



I 

 H — C — OH 



I 

 H— C— OH 



I 

 H— C— OH 



I 

 H 



-2H 



Flavin? 

 Cytochrome? 



c- 



I 



c- 



I 



HO— C- 



// 



H- 



■OH 

 -H 



-OH 



H 



H— C- 



I 

 C 



I 

 H— C— OH 



I 

 H 



HoO 



^. 



-OH 



H— C— OH 



I 

 HO— C— H 



H- 



-OH 



H— C— OH 



I 

 H— C— OH 



I 

 H 



6 - D - Gluconolactone 



Gluconic acid 



Fig. 1.2. Oxidation of glucose by particulate glucose oxidase in 

 A. siiboxydans. 



D-glucose oxidation by a particulate enzyme (see Fig. 1.2). 

 The optimum pH was 5.5 (11). A separate enzyme also 

 exists in this fraction, which hydrolyzes the lactone to d- 

 gluconic acid. Deoxycholate extracts of the particulate 

 fraction retained activity for oxidation of glucose, but they 

 no longer contained the hydrolyzing enzyme. 



"Soluble" Enzymes 



In addition, the cell-free extracts contained several soluble 

 enzymes that cooperate to effect the terminal oxidation of 

 glucose, other carbohydrates, and polyols. These were, for 

 the most part, phosphate-dependent and DPN- or TPN- 

 linked. Upon fractionation, the extracts were found to 

 contain the entire pentose cycle complex of enzymes (Fig. 

 1.3). 



