218 



PLANT BIOCHEMISTRY 



'O3POCH2CHOHCHO + 



_ — aldolase 



HOCHaCOCH.OPOa" ^ ^ 



H ho/ 

 H 



OH H 



cH.opo.; 



fructose-1,6- 

 diphosphatase 



'O^POCH., /O 



phosphoglucoisomerase 



OH 



glucose-6- 

 phosphatase 



l)-tj;lucose 



H 

 HO 



phosphogluco- 

 isomerase 



CH2OH 



—0, H 



HO H 



fructose - 6 - phosphate 



phosphomanno- 

 isomerase 



CH2OPO3" 



H 



OH H, 



opo.; 



H OH 



glucose-l- phosphate 



galactosephosphate 



epimerase 



DPN + 



HOCH., 



HO 



O. H 



phosphatase 



D-galactose 



OPO3- 

 H OH 



galactose-1-phosphate 



FIGURE 9-5. The formation of four hexoses as known in 1959. The reverse of 

 these processes is presented in Figure 7-1. A requirement for DPN+ has been 

 demonstrated in the galactosephosphate epimerase step, but the role played is un- 

 known. Apparently the DPN+ is not functioning in its normal role of hydrogen- 

 electron acceptor. 



