<prompt> Aldolase is an enzyme whose substrate isGlucose -6-phosphateFructose-6-phosphateFructoseFructose-1 biphosphate  <response>: Ans. d Fructose-1, biphosphateRef: Harpers Biochemistry, 30 ed. pg. 202-203th Aldolase B is preferentially expressed in the liver, while aldolase A is expressed in muscle and erythrocytes and aldolase C is expressed in the brain. Slight differences in isozyme structure result in different activities for the two substrate molecules: Fructose 1,6-Biphosphate and fructose 1-phosphate. Aldolase B exhibits no preference and thus catalyzes both reactions, while aldolases A and C prefer FBR Aldolase A is an enzyme that catalyses a reversible aldol reaction: The substrate, fructose 1,6-bisphosphate F- 1,6- BP is broken down into glyceraldehyde 3-phosphate and dihydroxyacetone phosphate DHAP. Sucrose is composed of glucose and fructose and hence cannot be tolerated by patients of HFI. 