Galactolysis
Galactolysis refers to the catabolism of galactose.
In the liver, galactose is converted through the Leloir pathway to glucose 6-phosphate in the following reactions:
galacto- uridyl phosphogluco-
kinase transferase mutase
gal --------> gal 1 P ------------------> glc 1 P -----------> glc 6 P
^ \
/ v
UDP-glc UDP-gal
^ /
\___________/
epimerase
Metabolic disorders
There are 3 types of galactosemia or galactose deficiencies:
Name | Enzyme | Description |
galactokinase deficiency | Galactokinase | Causes cataracts, which are treatable by restricting galactose from the diet. |
UDPgalactose-4-epimerase deficiency | UDPgalactose-4-epimerase | Is extremely rare (only 2 reported cases). It causes nerve deafness. |
Galactose-1-phosphate uridyl transferase deficiency | Galactose-1-phosphate uridyl transferase | Is the most problematic, as galactose-free diets are not effective in treating neurocognitive deficiencies (in particular language disorders such as verbal dyspraxia) and ovarian failure. If a galactose-free diet is administered, cataracts and acute symptoms such as kidney and liver failure respond immediately. |
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| General | |
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| Energy metabolism | Aerobic respiration | |
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- Electron acceptors are other than oxygen
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| Specific paths | |
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| Description |
- Metabolism
- Enzymes and pathways: citric acid cycle
- pentose phosphate
- glycoproteins
- glycosaminoglycans
- phospholipid
- cholesterol and steroid
- sphingolipids
- eicosanoids
- amino acid
- urea cycle
- nucleotide
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| Disorders |
- Citric acid cycle and electron transport chain
- Glycoprotein
- Proteoglycan
- Fatty-acid
- Phospholipid
- Cholesterol and steroid
- Eicosanoid
- Amino acid
- Purine-pyrimidine
- Heme metabolism
- Symptoms and signs
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| Treatment | |
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| Carbohydrates |
- Alcohols
- Glycoproteins
- Glycosides
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| Lipids |
- Eicosanoids
- Fatty acids
- Glycerides
- Phospholipids
- Sphingolipids
- Steroids
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| Nucleic acids | |
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| Proteins | |
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| Other |
- Tetrapyrroles
- intermediates
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| Fructose / Fructolysis | |
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| Sorbitol | |
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| Galactose / Galactolysis | |
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| Lactose | |
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| Mannose | |
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| Description |
- Metabolism
- Enzymes and pathways: citric acid cycle
- pentose phosphate
- glycoproteins
- glycosaminoglycans
- phospholipid
- cholesterol and steroid
- sphingolipids
- eicosanoids
- amino acid
- urea cycle
- nucleotide
|
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| Disorders |
- Citric acid cycle and electron transport chain
- Glycoprotein
- Proteoglycan
- Fatty-acid
- Phospholipid
- Cholesterol and steroid
- Eicosanoid
- Amino acid
- Purine-pyrimidine
- Heme metabolism
- Symptoms and signs
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| Treatment | |
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