Fructose Metabolism

Question 0

Important source of fructose is the disaccharide sucrose
-found in honey and fruits:
sucrose=fructose+glucose
Hydrolyzed by sucrose in the intestinal brush border

Among sugars, fructose has the fastest metabolism and greatest yield of energy

Answer 0

Fructose metabolism

Question 1

Phosphorylation of fructose

Answer 1

Fructose ➡️ fructose-1-phosphate

Enzyme: fructokinase or hexokinase

Question 2

Formation of DHAP and glyceraldehyde

Answer 2

Fructose-1-phosphate ➡️ dihydroxyacetone phosphate (DHAP)+glyceraldehyde

Enzyme: aldolase B

Question 3

Defect in fructokinase

Benign and asymptomatic whose only symptom is the appearance of fructose in blood and urine

Answer 3

Essential Fructosuria

Question 4

Deficiency of aldolase B

Autosomal recessive

Fructose-1-phosphate accumulates leading to ⬇️ phosphate, ⬇️ glycogenolysis and ⬇️ gluconeogenesis

Symptoms: hypoglycemia, jaundice, cirrhosis, vomiting

Tx: ⬇️ intake of fructose and sucrose

Answer 4

Fructose intolerance

Question 5

Fructosuria

Not evident while sole nutrition is beast milk

Severe hypoglycemia and lactic acidosis after fructose ingestion

Vomiting, apathy, diarrhea

Liver damage and jaundice

Proximal renal tubule disorder resembling Fanconi syndrome

Eliminate fructose from diet

Answer 5

Aldolase B deficiency