Carbohydrates in Aromatic Compound Biosynthesis 263 



From the F-6-P pool tetrose phosphate can then he formed by 

 reactions 3, 4, and 5 (Fig. 4), in which pentose phosphate and sedo- 

 heptulose-7-phosphate are intermediates." '- The net effect of these 

 reactions is to convert one molecule of F-6-P and two molecules of 



1C 



2C 1 c 



3C 3C 2C 



(3) J II 

 4>3C 3=4C 4>3C 3=4C 



I I TK 1 | 

 5>2C +2 = 5C > f>>2C + 2 = 5 C 



II II 



6 > 1 COP 1 = 6 COP 6 > 1 COP 1 = 6 COP 



1 C 



I 



1 C 2C 



2 C 3 C 3 C 



I I 1 



(4) (a)3 = 4C + 4>3C 1C +4>3C (a) 



I I TK | | 

 2 = .5C 5 > 2 C > 2 C 5 > 2 C 



II II 



1 = 6 COP 6 > 1 COP 1 C 6 > 1 COP 



I 

 2C 

 I 

 1C 1C 3=4C 3=4C 



TK | | 



2 C > 2 = 5 C + 2 = 5 C (6) 



I I I 



(fe) 3 = 4 C + 3 = 4 C 1=6 COP 1 = 6 COP 



2C 



I 



2=5C 2=5C 



I I 



1 = 6 COP 1 = 6 COP 



1C 



2C 1 C 



1C 2C 



(5) 2 C 2 C 1 C 



I I I 



3 = 4 C 3=4C 3 = 4C 3 = 4C 



I | TA | | 

 2 = 5 C +2 = 5C > 2 = 5C +2 = 5C 



II II 



1 = 6 COP 1 = 6 COP 1 = 6 COP 1 = 6 COP 



Fig. 4. Synthesis of tetrose phosphate via the pentose phosphate pathway from 

 the pooled F-6-P of reaction 1, Fig. 3. 



triose phosphate to three molecules of tetrose phosphate. In two of 

 these the "bottom" three carbon atoms are derived from the corre- 

 sponding atoms of F-6-P, and in the third tetrose molecule they are 

 derived from the triose phosphate. 



Iia> not been directly explored. The phosphatase required for reaction 2 has 

 been demonstrated in preliminary experiments on extracts of this strain of E. coli. 

 (P. R. Srinivasan and D. B. Sprinson, unpublished results. We are indebted to 

 Dr. E. Racker for generous supplies of purified FDP and glucose-6-phosphate 

 dehydrogenase required in this assay). 



