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 nucleotide ...

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. For ...

in a hydrophobic interaction. It was not able to be removed by the error-correcting machinery of the ''

E. coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escher ...

'' into which it was inserted. The pairing of d5SICS–dNaM is mediated by packing and

hydrophobic force The hydrophobic effect is the observed tendency of nonpolar substances to aggregate in an aqueous solution and exclude water molecules. The word hydrophobic literally means "water-fearing", and it describes the segregation of water and nonpolar ...

s 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 a l ...

, which occurs in natural base pairs. Therefore, in free DNA,

rings Ring may refer to: * Ring (jewellery), a round band, usually made of metal, worn as ornamental jewelry * To make a sound with a bell, and the sound made by a bell :(hence) to initiate a telephone connection Arts, entertainment and media Film and ...

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