Fructose and Galactose Metabolism Flashcards
How does fructose enter enterocytes and other cells?
via GLUT 5 transporter
Where is Aldolase A present?
cells of muscle and most other tissues
Where is Aldolase B present?
cells of liver, kidney, small intestine
Where is Aldolase C present?
cells of the brain
What is the rate limiting enzyme of fructose metabolism?
Aldolase B
fructose cannot be converted to fructose 1-phosphate in what disorder?
Essential fructosuria
deficiency or defect in aldolase B which decreases the availablity of ATP
- hyperuricemia
- lactic acidosis
Hereditary fructose intolerance
What converts fructose to fructose-1-phosphate?
fructokinase
Fructose-1-phosphate is cleaved by what to form DHAP and glyceraldehyde?
Aldolase B
What converts glyceraldehyde to glyceraldehyde-3-phosphate?
triose kinase
a deficiency in fructokinase causes what disorder?
essential fructoseuria
when does the first symptom of hereditary fructose intolerance occur?
when the baby is weaned from milk and foods with sucrose or fructose are introduced
What accumulates in uncontrolled DM and contributes to diabetes complications?
sorbitol
what catalyzes the exchange of UDP and phosphate between galactose 1-phosphate and UDP-glucose?
Galactose 1-phosphate uridyl transferase (GALT)
deficiency of galactokinase where galactose accumulates in the cells and hence in the blood (galactosemia) and appears in the urine (galactosuria)
- NO mentak retartadtion
- bilateral cataracts
- tx: restriction of milk
Non classical galactosemia
