INTERCONVERSION OF SUGARS 



channel in most cells, but it is quite likely that the same type 

 of reaction may be used for other purposes. The equilibrium is 

 strongly displaced in favor of fructose diphosphate, so that trap- 

 ping agents such as cyanide or bisulfite are used in order to detect 

 triose phosphate formation. 



Meyerhof and Lohmann found that when aldolase was 

 mixed with fructose diphosphate and different aldehydes, there 

 occurred a transference of the dihydroxyacetone phosphate por- 

 tion to the added aldehyde. Several of such transference reac- 

 tions have been observed. Thus, D-fructose-1 -phosphate (XIII) 

 is formed on incubating aldolase with fructose-l,6-diphosphate 

 and D-glyceraldehyde. With L-glyceraldehyde the product is 

 L- sorbose- 1 -phosphate (XIV); with glycolaldehyde it is d- 

 xylulose-1 -phosphate (XV); with acetaldehyde it is probably 

 5-deoxyxylulose-l -phosphate (XVI) ; and with tetrose phosphate 

 it is sedoheptulose-l,7-diphosphate. 



CH2OPO3— CH2OPO3-- 



CO CO 



I I 



HOCH HOCH 



HCOH HCOH 



I I 



HCOH HOCH 



CH2OH CHoOH 



(xni) (XIV) 



D-Fructose- 1 -phosphate L-Sorbose- 1 -phosphate 



CH2OPO3-- . CH2OPO3— 



CO GO 



I I 



HOCH HOCH 

 I 1 



HCOH HCOH 



CH2OH CH3 



(XV) (XVI) 



D-Xylulose-1 -phosphate 5-Deox>^ylulose-l -phosphate 



The synthetic products obtained with aldolase are believed 

 to have the OH at carbons 3 and 4 always in the trans position 



595 



