Structural Biochemistry/Nucleic Acid/Nitrogenous Bases/Purines/Hypoxanthine

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Hypoxanthine[edit]

Hypoxanthine (6-Hydroxypurine) is a naturally occurring purine derivative and deaminated form of adenine. It is an intermediate in the purine catabolism reaction and is occasionally found as a constituent in the anticodon of tRNA as the nucleosidic base inosine. It is also utilized as a nitrogen source in bacteria and parasite cultures for energy metabolism and nucleic acid synthesis.

Hypoxanthine .jpg

Reactions[edit]

Hypoxanthine exists as an intermediate in the biodegradation of AMP (adenosine monophosphate). It is fist converted to xanthine with xanthine oxidase before it is excreted as urate.

Urate reaction.jpg

A deleterious reaction that can occur is a spontaneous deamination of adenine to form hypoxanthine. This is a mutagenic process because the result is a pairing of hypoxanthine with cytosine rather than thymine, due to hypoxanthine’s guanine-like form. This could lead to an error in DNA transcription and replication.

Adenine deaminase scheme.jpg


References[edit]

Berg, et al. Biochemistry, 6th Ed. 2007.