Explain the chemical logic of converting glucose to fructose

Explain the chemical logic of converting glucose to fructose before aldolase splits the sugar in two

Solution

The second reaction in the glycolysis is the conversion of Glucose-6-phosphate to Fructose-6-phosphate. This reaction is catalysed by enzyme Isomerase. This reaction involves the rearrangement of carbon-oxygen bond to transform the six-membered ring to a five-membered ring. The rearrangement takes place when 6 carbon membered ring opens and closes so that first carbon becomes external to the ring. Afterwards, Fructose-6-phosphate forms fructose-1,6-biphosphate.

Glucose-1,6-phosphate-----------^isomerase----------> Fructose-1,6-biphosphate

Fructose-1,6-biphosphate--------^aldolase-----------------> Dihydroxyacetone phosphate + Glyceraldehyde-3-phosphate

The above conversion of glucose to fructose-1,6-biphosphate occur so that the enzyme aldolase can break the carbon-carbon bond to form two sugars. The aldolase enzyme has specific receptors for fructose.