POLYSACCHARIDES OF MICRO-ORGANISMS 367 



gl^culaldehyde, which coiideiuses to give glucose aiid 

 finally glycogen. In summary, three molecules of lactic 

 acid give one molecide of glucose and three molecules of 

 carbon dioxide and water : — 



3CH3CHOH.COOH + 30^ ^ 3CO2 + 3H2O + CeHioOg. 



Or we may regard the process as being the oxidation of 

 one-third of the lactic acid to provide the energy for the 

 synthesis of the other two -thirds to glucose and 

 glycogen :— 



CH3CHOH.COOH + 3O2 > 3CO2 + 3H2O (energy). 



2CH3CHOH.COOH > CeHiaOg (synthesis). 



Hanes showed that starch was synthesised from glu- 

 cose- 1 -phosphate under the influence of an enzyme, 

 phosphorylase, present in potatoes, inorganic phosphate 

 being liberated during the process. It has been suggested 

 as a possible general mechanism that glucose is phos- 

 phorylated at the expense of adenosine triphosphate, as 

 in yeast fermentation, and that some of the ester may be 

 acted on by enzymes other than the normal fermentation 

 enzymes to give rise to polysaccharides : — 



Glucose + adenosine triphosphate 



Hexokinase (in yeast, animal 



T tissues) 



Isomerase | ' 



Fructose-G-phosphate ^=1:1^=:===^ glucose-G-phosphate + adenosine 



30% diphosphate 



1j Q-Q, Phosphoglucomutase 



\l '° (yeast, animal tissues 

 Glucose - 1 -phosphate 



'jl „m^, Phosphorylase (yeast 

 I '° potatoes, muscle and 

 kidney) 

 Polysaccharide + phosphate 



The necessary energy for the process is held to be 

 derived from the conversion of adenosine triphosphate to 

 the di -phosphate. The latter is re-esterified to adenosine - 

 riphosphate by the phosphate set free in the final stage 



