Guanine deaminase

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Guanine deaminase

Guanine deaminase (GDA), also known as guanase, is an enzyme that catalyzes the deamination of guanine to xanthine and ammonia. This enzyme plays a crucial role in the purine metabolism pathway, which is essential for the degradation and synthesis of nucleotides.

Function

Guanine deaminase is responsible for the hydrolytic deamination of guanine, a purine base found in DNA and RNA. The reaction it catalyzes can be summarized as follows: <math>Guanine + H_2O \rightarrow Xanthine + NH_3</math>

This reaction is a part of the purine catabolism process, which ultimately leads to the production of uric acid in humans. The enzyme helps maintain the balance of purine bases within the cell and prevents the accumulation of toxic levels of guanine.

Structure

Guanine deaminase is a protein that typically functions as a homodimer. Each subunit of the enzyme contains an active site where the deamination reaction occurs. The enzyme requires a zinc ion as a cofactor for its catalytic activity.

Tissue Distribution

Guanine deaminase is expressed in various tissues throughout the body, with higher levels found in the liver, kidney, and brain. Its activity is crucial in tissues with high rates of nucleotide turnover and purine metabolism.

Clinical Significance

Abnormalities in guanine deaminase activity can lead to disorders in purine metabolism. For instance, deficiencies in this enzyme can result in the accumulation of guanine, which may contribute to the development of certain metabolic disorders. Research is ongoing to understand the full implications of guanine deaminase in human health and disease.

Related Enzymes

Guanine deaminase is part of a family of enzymes involved in purine metabolism, including adenosine deaminase and xanthine oxidase. These enzymes work in concert to regulate the levels of purine bases and their derivatives in the body.

See Also

• Purine metabolism
• Xanthine
• Adenosine deaminase
• Xanthine oxidase
• Nucleotide
• DNA
• RNA