- CARMA SEMINAR
- Speaker: Xian'an Jin, School of Mathematics, Xiamen University
- Title: DNA and protein polyhedral links
- Location: Room V206, Mathematics Building (Callaghan Campus) The University of Newcastle
- Time and Date: 3:00 pm, Mon, 10th Feb 2014
Polyhedral links, interlinked and interlocked architectures, have been proposed for the description and characterization of DNA and protein polyhedra. Chirality is a very important feature for biomacromolecules. In this talk, we discuss the topological chirality of a type of DNA polyhedral links constructed by the strategy of "n-point stars and a type of protein polyhedral links constructed by "three-cross curves" covering. We shall ignore DNA sequence and use the orientation of the 2 backbone strands of the dsDNA to orient DNA polyhedral links, thus consider DNA polyhedral links as oriented links with antiparallel orientations. We shall ignore protein sequence and view protein polyhedral links as unoriented ones. It is well known that there is a correspondence between alternating links and plane graphs. We prove that links corresponding to bipartite plane graphs have antiparallel orientations, and under these orientations, their writhes are not zero. As a result, the type of right-handed double crossover 4-turn DNA polyhedral links are topologically chiral. We also prove that the unoriented link corresponding to a connected, even, bipartite plane graph has self-writhe 0 and using the Jones polynomial we present a criterion for chirality of unoriented alternating links with self-writhe 0. By applying this criterion we obtain that 3-regular protein polyhedral links are also topologically chiral. Topological chirality always implies chemical chirality, hence the corresponding DNA and protein polyhedra are all chemically chiral. Our chiral criteria may be used to detect the topological chirality of more complicated DNA and protein polyhedral links to be synthesized by chemists and biologists in the future.
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