Molecular knot
[1] Naturally-forming molecular knots are found in organic molecules like DNA, RNA, and proteins.
[1] The term knotane was coined by Vögtle et al. in 2000 to describe molecular knots by analogy with rotaxanes and catenanes, which are other mechanically interlocked molecular architectures.
Organic molecules containing knots may fall into the categories of slipknots or pseudo-knots.
[7] A number of proteins containing naturally occurring molecular knots have been identified.
[7] Artificial DNA, RNA, and protein knots have been successfully synthesized.
Molecular knots are often synthesized with the help of crucial metal ion ligands.
[7] The first researcher to suggest the existence of a molecular knot in a protein was Jane Richardson in 1977, who reported that carbonic anhydrase B (CAB) exhibited apparent knotting during her survey of various proteins' topological behavior.
[30] However, the researcher generally attributed with the discovery of the first knotted protein is Marc.
[31] In 1989, Sauvage and coworkers reported the first synthetic knotted molecule: a trefoil synthesized via a double-helix complex with the aid of Cu+ ions.
[17] Vogtle et al. was the first to describe molecular knots as knotanes in 2000.
[32] With this study, Taylor confirmed the existence of deeply knotted proteins.
In 2007, Eric Yeates reported the identification of a molecular slipknot, which is when the molecule contains knotted subchains even though their backbone chain as a whole is unknotted and does not contain completely knotted structures that are easily detectable by computational models.
[33] Mathematically, slipknots are difficult to analyze because they are not recognized in the examination of the complete structure.
A pentafoil knot prepared using dynamic covalent chemistry was synthesized by Ayme et al. in 2012, which at the time was the most complex non-DNA molecular knot prepared to date.
[28] An important development in knot theory is allowing for intra-chain contacts within an entangled molecular chain.
et al., developed a singular knot theory that is applicable to folded linear chains with intramolecular interactions.
[35] Many synthetic molecular knots have a distinct globular shape and dimensions that make them potential building blocks in nanotechnology.
