Galactokinase

Galactokinase is an enzyme that facilitates the phosphorylation of alpha-D-galactose to galactose 1-phosphate at the expense of one molecule of Adenosine triphosphate (ATP). Galactokinase is a key enzyme for the galactose metabolism pathway. The enzyme is encoded by the GALK1 gene in humans.

Function

Galactokinase plays a crucial role in the Leloir pathway, a metabolic pathway found in most organisms for the catabolism of β-D-galactose to glucose 1-phosphate. The absence or deficiency of galactokinase leads to a buildup of galactose in the body, resulting in galactosemia, a potentially life-threatening condition.

Structure

The GALK1 gene encoding galactokinase is located on the short (p) arm of chromosome 17 at position 24. The enzyme is composed of two identical subunits, each containing a single active site. The active site consists of three regions: the sugar binding site, the ATP binding site, and the aspartate residue.

Clinical significance

Galactokinase deficiency is a type of galactosemia, and it results from a mutation in the GALK1 gene. This condition increases the amount of galactose in the blood, leading to complications such as cataracts, delayed development, and speech difficulties. Early diagnosis and dietary restrictions can prevent or alleviate these symptoms.

See also

• Galactosemia
• Leloir pathway
• Enzyme

References

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  Galactokinase mechanism
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  Galactokinase crystal structure