guanine metabolic process

Definition

Target type: biologicalprocess

The chemical reactions and pathways involving guanine, 2-amino-6-hydroxypurine, a purine that is one of the five main bases found in nucleic acids and a component of a number of phosphorylated guanosine derivatives whose metabolic or regulatory functions are important. [GOC:go_curators]

Guanine metabolism is a complex and essential biological process that involves the synthesis, degradation, and interconversion of guanine, a purine base. This process is crucial for the production of DNA, RNA, and other essential biomolecules.

**Guanine Synthesis:**

1. **De novo purine biosynthesis:** Guanine is synthesized from simpler precursors, such as amino acids and tetrahydrofolate, through a series of enzymatic reactions.
2. **Salvage pathway:** Guanine can also be recycled from existing purine bases, such as hypoxanthine and xanthine.

**Guanine Degradation:**

1. **Guanine deaminase:** Guanine is deaminated to xanthine by the enzyme guanine deaminase.
2. **Xanthine oxidase:** Xanthine is further oxidized to uric acid by xanthine oxidase.
3. **Uric acid excretion:** Uric acid is the final product of purine degradation in humans and is excreted in the urine.

**Interconversion of Guanine with Other Purines:**

1. **Hypoxanthine-guanine phosphoribosyltransferase (HGPRT):** This enzyme catalyzes the conversion of hypoxanthine to inosine monophosphate (IMP) and guanine to guanosine monophosphate (GMP).
2. **GMP synthetase:** This enzyme converts IMP to GMP, using glutamine as an amino group donor.

**Regulation of Guanine Metabolism:**

Guanine metabolism is tightly regulated to maintain appropriate levels of purine nucleotides.

1. **Feedback inhibition:** The synthesis of purine nucleotides is inhibited by high concentrations of these nucleotides.
2. **Hormonal regulation:** Hormones such as insulin and growth hormone can stimulate purine synthesis.
3. **Dietary intake:** The intake of purine-rich foods can affect purine metabolism.

**Disorders of Guanine Metabolism:**

Defects in guanine metabolism can lead to various diseases, including:

1. **Lesch-Nyhan syndrome:** A rare X-linked recessive disorder caused by a deficiency in HGPRT, leading to hyperuricemia, neurological abnormalities, and self-mutilation.
2. **Gout:** A metabolic disorder characterized by the accumulation of uric acid in the joints, leading to inflammation and pain.

**Clinical Significance:**

The understanding of guanine metabolism is critical for the diagnosis and treatment of various diseases.

1. **Diagnosis:** Measuring purine metabolites in blood and urine can be used to diagnose disorders of guanine metabolism.
2. **Treatment:** The treatment of these disorders may involve dietary modifications, medications to inhibit purine synthesis or uric acid production, or enzyme replacement therapy.'
"

Proteins (2)

Compounds (56)