Guanine

Guanine is one of the four main nucleobases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, and thymine (uracil in RNA). In DNA, guanine is paired with cytosine. With the formula C5H5N5O, guanine is a derivative of purine, consisting of a fused pyrimidine-imidazole ring system with conjugated double bonds.

Structure and Properties

Guanine, along with adenine and cytosine, is present in both DNA and RNA, whereas thymine is usually seen only in DNA, and uracil only in RNA. Guanine has two tautomeric forms, the major keto form (see figures) and rare enol form.

Functions

Guanine is a vital component of genetic material - DNA and RNA. It forms the building blocks of these genetic materials. In the DNA, guanine binds with cytosine through three hydrogen bonds, stabilizing the DNA molecule and maintaining the structure of the double helix.

Synthesis

Guanine, like most other nucleobases, is made from simple organic molecules in a series of reactions known as a metabolic pathway. This is a complex process that requires a series of enzymes, each of which catalyzes a specific reaction.

Medical Significance

Guanine is crucial for a variety of biological functions, including cell division, and the regulation of gene expression and signal transduction. Mutations in the guanine nucleotide can lead to errors in these processes and cause a variety of diseases.

See Also

• Adenine
• Cytosine
• Thymine
• Uracil
• DNA
• RNA

References

Guanine Resources
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