Metabolism of Inositol 



195 



C0 2 . Similar patterns were observed in the anaerobic degradations 

 of glucose and the cyclitols. Glucose yielded acid, but no C0 2 ; in the 

 presence of As 2 3 glucose was converted to 2 moles of lactic acid per 

 mole. On the other hand, myo-'mositol, as well as its keto derivatives, 

 was fermented with the production of 1 mole of C0 2 per mole of sub- 

 strate. In the presence of As 2 3 myoinositol was converted to an 



D- Glucose 



C, + C, 



myo- Inositol 



-2H 



03 + 0;;+ Cj -« O 



2 - Keto - myo ■ 

 inositol 



L-l,2-Diketo- 

 tnyo - inositol 



C.i H fi O : 



6 W 3 



+ 3C0 2 . 



CjHgO,-, 



+ 3C0 2 



Fig. 5. The proposed pathways of degradation of glucose and of myo-inositol in 



Material assimilated. 



A. aerogenes. 



C 3 H 6°3 



equimolar mixture of C0 2 , ethanol, and lactic acid; apparently pyru- 

 vate and acetate (or an active form of acetate) can serve as hydrogen 

 acceptors in the dehydrogenation steps (reactions la and 3). 



Thus glucose and m^/o-inositol are metabolized by A. aerogenes by 

 different pathways to the same final products (Fig. 5). The direct 

 conversion of my o -inositol to glucose by cleavage of the bond between 

 carbon atoms 3 and 4 which has frequently been postulated does not 

 occur in this system. However, the production of pyruvate from myo- 

 'mositol by a pathway corresponding to the one described in A. aero- 

 genes could well explain the antiketogenic effect of ra?/o-inositol, and 

 the conversion of stably bound deuterium in ???i/o-inositol to stably 

 bound deuterium in glucose which have been observed in the rat. 2 



The pathway of inositol degradation is superficially similar to the 



