d5SICS is an artificial

nucleoside Nucleosides are glycosylamines that can be thought of as nucleotides without a phosphate group. A nucleoside consists simply of a nucleobase (also termed a nitrogenous base) and a five-carbon sugar ( ribose or 2'-deoxyribose) whereas a nucleoti ...

containing 6-methyl

isoquinoline Isoquinoline is a heterocyclic aromatic organic compound. It is a structural isomer of quinoline. Isoquinoline and quinoline are benzopyridines, which are composed of a benzene ring fused to a pyridine ring. In a broader sense, the term isoquin ...

-1-thione-2-yl group instead of a base. It pairs up with

dNaM dNaM is an artificial nucleobase containing a 3-methoxy-2-naphthyl group instead of a natural base. When it was originally successfully introduced into DNA for replication in an E. coli semi-synthetic organism, it was paired up with d5SICS. Fo ...

in a hydrophobic interaction. It was not able to be removed by the error-correcting machinery of the '' E. coli'' into which it was inserted. The pairing of d5SICS–dNaM is mediated by packing and hydrophobic forces instead of

hydrogen bonding In chemistry, a hydrogen bond (or H-bond) is a primarily electrostatic force of attraction between a hydrogen (H) atom which is covalently bound to a more electronegative "donor" atom or group (Dn), and another electronegative atom bearing ...

, which occurs in natural base pairs. Therefore, in free DNA, rings of d5SICS and dNaM are placed in parallel planes instead of the same plane. The d5SICS-dNaM pairing replaced an older dNaM- dTPT3 pairing.

References

Nucleosides Synthetic biology Thioketones Nitrogen heterocycles Heterocyclic compounds with 2 rings {{molecular-biology-stub