Aldose 1-epimerase

Aldose 1-epimerase is an enzyme that catalyzes the reversible conversion of aldoses to their epimers at the carbon-1 position. This enzyme plays a crucial role in carbohydrate metabolism, particularly in the interconversion of glucose and galactose, which is a key step in the utilization of galactose obtained from the diet. Aldose 1-epimerase is also known by several other names, including galactose mutarotase and GALT. It is encoded by the gene GALM in humans.

Function

Aldose 1-epimerase facilitates the conversion of alpha-aldose to beta-aldose and vice versa. This reaction is essential for the proper metabolism of carbohydrates, as it allows for the interconversion of different forms of sugars, enabling their utilization as energy sources or their conversion into other biochemical compounds. The enzyme's activity is particularly important in the Leloir pathway, the primary pathway for galactose metabolism, where it converts galactose to glucose and vice versa.

Structure

The enzyme is a monomer that binds one magnesium ion per monomer, which is essential for its catalytic activity. The structure of aldose 1-epimerase includes several key domains responsible for substrate binding and catalysis. The active site of the enzyme is where the conversion of aldoses occurs, and it is highly specific for its substrates.

Clinical Significance

Mutations in the GALM gene, which encodes aldose 1-epimerase, can lead to disorders of galactose metabolism. One of the most significant conditions related to this enzyme's dysfunction is galactosemia, a rare genetic disorder that affects the body's ability to process galactose properly. Patients with galactosemia may suffer from a range of symptoms, including liver dysfunction, cognitive impairment, and in severe cases, early mortality. Early diagnosis and dietary management can mitigate some of the adverse effects associated with this condition.

See Also

• Enzyme
• Carbohydrate metabolism
• Galactosemia
• Leloir pathway