Topology is the mathematical study of the spatial properties that are preserved through the deformation, twisting and stretching of objects. Topological architectures are common in nature and can be seen, for example, in DNA molecules that condense and relax during cellular events. Synthetic topological nanostructures, such as catenanes and rotaxanes, have been engineered using supramolecular c...

Transformation of mechanically interlocked molecules (e.g., rotaxanes and catenanes) into nanoscale materials or devices is an important step towards their real applications. In our current work, an azobenzene-modified β-cyclodextrin (β-CD) derivative that can form a self-inclusion complex in aqueous solution was prepared. The self-included β-CD derivative was then functionalized onto a gold na...

The contribution of DNA catenation to sister chromatid cohesion is unclear partly because it has never been observed directly within mitotic chromosomes. Differential sedimentation-velocity and gel electrophoresis reveal that sisters of 26 kb circular minichromosomes are held together by catenation as well as by cohesin. The finding that chemical crosslinking of cohesin's three subunit interfac...

More than three decades of research efforts have yielded powerful methodologies based on transition metal template-directed syntheses for the assembly a huge number interlocked systems, molecular knots, machines and synthesizers. Such template techniques been applied in preparation mechanically linked electron donor–acceptor artificial photosynthetic models. Consequently, synthetic challenging ...

Together, RecQ helicase and topoisomerase III (Topo III) of Escherichia coli comprise a potent DNA strand passage activity that can catenate covalently closed DNA (Harmon, F. G., DiGate, R. J., and Kowalczykowski, S. C. (1999) Mol. Cell 3, 611-620). Here we directly assessed the structure of the catenated DNA species formed by RecQ helicase and Topo III using atomic force microscopy. The images...

Over the last two decades, researchers have focused on the synthesis and development of mechanically interlocked molecules (MIMs). The intramolecular motion of mechanical bonds and the ability to induce this effect with the choice of the proper external stimuli has prompted the development of macromolecular systems that possess the ability to "perform work" at the molecular level. Currently, re...

The development of a simple approach to studying self-assembly processes in the chemical laboratory began with an investigation of the donor/acceptor complexes formed between (a) crown ethers, like bisparaphenylene-34crown10, and 4,4 '-bipyridinium dications, such as paraquat, and (b) tetracationic cyclophanes, like cyclobis(paraquat-p-phenylene), and neutral substrates, such as 1.4dimethoxyben...

The classical X shape of mitotic human chromosomes is the consequence of two distinct waves of cohesin removal. First, during prophase and prometaphase, the bulk of cohesin is driven from chromosome arms by the cohesin antagonist WAPL. This arm-specific cohesin removal is referred to as the prophase pathway [1-4]. The subsequent cleavage of the remaining centromeric cohesin by Separase is known...