Hypoxanthine is a naturally occurring purine derivative. It is occasionally found as a constituent of nucleic acids where it is present in the anticodon of tRNA in the form of its nucleoside inosine. It is also known as 6-Hydroxypurine. Hypoxanthine is a necessary additive in certain cell, bacteria, and parasite cultures as a substrate and nitrogen source. For example, it is commonly a required reagent in malaria parasite cultures, since Plasmodium falciparum requires a source of hypoxanthine for nucleic acid synthesis and energy metabolism.
It is one of the products of the action of xanthine oxidase on xanthine. However, more frequently in purine degradation, hypoxanthine is formed from reduction of xanthine by xanthine oxidoreductase.
Hypoxanthine-guanine phosphoribosyltransferase converts hypoxanthine into IMP in nucleotide salvage.
Hypoxanthine is also a spontaneous deamination product of adenine. Because of its resemblance to guanine, the spontaneous deamination of adenine can lead to an error in DNA transcription/replication.
Adenine. Notice the extra nitrogen compared to the oxygen in hypoxanthine. (Disregard the fact that the rings are in opposite positions.)
R5P→IMP: R5P · PRPP · PRA · GAR · FGAR · FGAM · AIR · CAIR · SAICAR · AICAR · FAICAR
mt, r/g/c/p/i/y, f/h/s/l/o/e, a/u, n, h
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