Galactolysis refers to the catabolism of galactose.
In the liver, galactose is converted through the Leloir pathway to glucose 6-phosphate[1] 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
Mutations in the enzymes involved in galactolysis result in metabolic disorders.[2]
Metabolic disorders
[edit]There are 3 types of galactosemia or galactose deficiencies:
Name | Enzyme | Description |
galactokinase deficiency | Galactokinase | Causes cataracts, which form due to the elevation of galactitol that accumulates when galactose is metabolized in an alternative pathway that is not the Leloir pathway.[2] These 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. Formation of cataracts is similar to that in galactokinase deficiency.[2] |
References
[edit]- ^ Holden, Hazel M.; Rayment, Ivan; Thoden, James B. (7 November 2003). "Structure and Function of Enzymes of the Leloir Pathway for Galactose Metabolism". Journal of Biological Chemistry. 278 (45): 43885–43888. doi:10.1074/jbc.R300025200. PMID 12923184.
- ^ a b c Demirbas, Didem; Coelho, Ana I.; Rubio-Gozalbo, M. Estela; Berry, Gerard T. (June 2018). "Hereditary galactosemia". Metabolism. 83: 188–196. doi:10.1016/j.metabol.2018.01.025. PMID 29409891.
- ^ Beebe, Jane A.; Frey, Perry A. (1998-10-01). "Galactose Mutarotase: Purification, Characterization, and Investigations of Two Important Histidine Residues". Biochemistry. 37 (42): 14989–14997. doi:10.1021/bi9816047. ISSN 0006-2960.
Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction