The elasticity of DNA catenanes, i.e. multiply linked DNA rings, is investigated using the Gauss invariant as a minimal model for topology conservation. An effective elastic free energy as a function of the distance R between segments located on different rings is obtained. An anharmonic part at large distances, growing as R 4 , if R ≫ RG (RG being the radius of gyration of a random walk ring) ...

The topology of DNA duplexes changes during replication and also after deproteinization in vitro. Here we describe these then discuss for the first time how distribution superhelical stress affects intermediates, taking into account progression forks. high processivity Topo IV to relax left-handed (+) supercoiling that transiently accumulates ahead forks is not essential, since gyrase swiveling...

Two three-dimensional catenanes have been successfully synthesized from a bis(m-phenylene)-32-crown-10-based cryptand and paraquat derivatives in reasonable yields.

Mechanically interlocked structures such as rotaxanes and catenanes provide a novel backbone for constructing functional materials with unique structural characteristics. In this study, we have designed and synthesized a series of photoswitchable rotaxanes and catenanes containing photochromic dithienylethene fragments using a template-directed clipping approach based on dynamic imine chemistry...

Recent investigations on the design and synthesis of electrochromic materials based on switchable three-station [2]catenanes are summarized. The reasoning and preliminary experiments behind the design of electrochemically controllable red-green-blue (RGB), donor-acceptor [2]catenanes are presented. A basis for color generation is discussed in which the tetracationic cyclophane, cyclobis(paraqua...

sites from the Drosophila gypsy transposon and the The Xenopus rRNA enhancer activates its cognate chicken b-globin insulator, have been suggested. These promoter when the two elements are placed on oppoinclude higher order chromatin structure (Udvardy et al., site rings of dimeric catenanes. Here we show that 1985; Kellum and Schedl, 1991; Vasquez and Schedl, when scs elements flank either the...

Donor-acceptor [2]catenanes based on cyclobis(paraquat-p-phenylene) as the pi-acceptor ring have been used prominently in the construction of functional molecular devices. We report here their thermodynamically controlled synthesis from isolated pi-donor and pi-acceptor rings under the catalytic influence of tetra butylammonium iodide. The initial nucleophilic attack of iodide ion, which opens ...

The influences of different physical environments on the thermodynamics associated with one key step in the switching mechanism for a pair of bistable catenanes and a pair of bistable rotaxanes have been investigated systematically. The two bistable catenanes are comprised of a cyclobis(paraquat-p-phenylene) (CBPQT4+) ring, or its diazapyrenium-containing analogue, that are interlocked with a m...