Lysidine (nucleoside)

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Lysidine (nucleoside)
IUPAC name
2-Amino-6-[4-amino-1-(3,4-dihydroxy-5-hydroxymethyloxolan-2-yl)-1H-pyrimidin-2-ylideneamino]hexanoic acid
Other names
3D model (Jmol)
Molar mass 371.39 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Lysidine is an uncommon nucleoside, rarely seen outside of tRNA. It is a derivative of cytidine in which the carbonyl is replaced by the amino acid lysine. The third position in the anti-codon of the Isoleucine-specific tRNA, is typically changed from a cytidine which would pair with guanosine to a lysidine which will base pair with adenosine. Uridine could not be used at this position even though it is a conventional partner for adenosine since it will also "wobble base pair" with guanosine. So lysidine allows better translation fidelity.[1][2]

Lysidine base pairs with Adenosine in context of a Cytosine to Guanosine base pair. R = ribose. Arrows indicate hydrogen bonds going from hydrogens to bond acceptor. The notation for lysidine, L, is depicted above.