370 IMMUNO-CATALYSIS 



molecule of glucose. From the above relationships it is evident that 

 about 40 per cent of the free energy liberated by one mole of glucose 

 fermented is converted into energy utilizable by the living cell. The 

 rest of the energy is dissipated in the form of heat. 



Description of the Reactions. 



( 1 ) In the presence of inorganic phosphate, glycogen or starch is 

 reversibly converted into glucose- 1 -phosphate. This reversible 

 reaction is catalyzed by fhosfhorylase. Adenylic acid functions 

 as coenzyme. Reducing agents activate phosphorylase. Traces 

 of glycogen are necessary as "priming" agent for the synthesis 

 of glycogen from glucose- 1 -phosphate. Glucose inhibits phos- 

 phorylase activity. 



(2) Phosfhogliwomutase converts glucose- 1- to glucose-6-phos- 

 phate. The reaction is reversible; Mg^'*', Mn+ + , or Co"^+ in- 

 crease the activity of the enzyme. 



(3) Hexokinase, in the presence of ATP and Mg+ + , phosphoryl- 

 ates glucose into glucose-6-phosphate. ATP serves as phosphate 

 donator, ATP ^ ADP. 



(4) Phosphatase hydrolyzes glucose-6-phosphate, yielding glucose 

 and inorganic phosphate. 



(5) Fhosfhohexose isomerase converts glucose-6-phosphate to fruc- 

 tose-6-phosphate. 



(6) Vhosfhatase hydrolyzes fructose-6-phosphate into fructose and 

 inorganic phosphate. 



(7) Hexokinase, in the presence of ATP and Mg^"^, phosphoryl- 

 ates fructose, yielding fructose-6-phosphate. 



(8) Fructose-6-phosphate is converted into fructose-l,6-diphos- 

 phate. ATP and Mg++ are required. The enzyme respon- 

 sible for this reaction has not been adequately studied. 



(9) Fructose- 1,6-diphosphate can be hydrolyzed into fructose-6- 

 phosphate by fhos-phatase. 



(10) Aldolase reversibly splits fructose- 1,6-diphosphate into dihy- 

 droxyacetone and d-3-phosphoglyceraldehyde. 



(11) Phosphotriose isomerase rapidly establishes the equilibrium 

 between the two triose phosphates produced in reaction (10). 



(12) Dehydrogenase reversibly reduces dihydroxyacetone phosphate 

 to 1-a-glycerophosphate. 



