Topic overview

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Fructokinase phosphorylates fructose to fructose-1-phosphate, which aldolase B cleaves into DHAP and glyceraldehyde; triose kinase converts glyceraldehyde to glyceraldehyde-3-phosphate. These products enter central metabolic pathways downstream of phosphofructokinase-1, helping explain fructose’s distinct metabolic effects. The lesson also links enzyme defects to disease: fructokinase deficiency causes benign essential fructosuria, while aldolase B deficiency causes hereditary fructose intolerance, with phosphate trapping and impaired glucose production. Finally, the sorbitol pathway connects glucose and fructose metabolism to tissue-specific effects and complications of sorbitol accumulation. Together, these pathways provide a framework for understanding fructose handling and its clinical implications.