Thermal unfolding curves have been measured for a series of short alanine-based peptides that contain repeating sequences and varying chain lengths. Standard helix-coil theory successfully fits the observed transition curves, even for these short peptides. The results provide values for sigma, the helix nucleation constant, delta H0, the enthalpy change on helix formation, and for s (0 degree C...

Cytoskeletal motors include myosins, kinesins and dyneins. Myosins move along tracks of actin filaments, whereas kinesins and dyneins move along microtubules. Many of these motors are involved in trafficking cargo in cells. However, myosins are mostly monomeric, whereas kinesins are mostly dimeric, owing to the presence of a coiled coil. Some myosins (myosins 6, 7 and 10) contain an SAH (single...

E. Y. Wong, C. M. Hillenbrand, J. S. Lewin, J. L. Duerk Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States, Department of Radiology, University Hospitals of Cleveland, Cleveland, OH, United States Introduction The use of MRI in minimally invasive, intravascular therapeutic procedures, has increased the need for imaging coils that provide accurate...

Coiled carbon nanotubes were produced catalytically by thermal decomposition of hydrocarbon gas. After deposition on a silicon substrate, the three-dimensional structure of the helix-shaped multiwalled nanotubes can be visualized with atomic force microscopy. Helical structures of both chiralities are present in the nanotube deposits. For larger coil diameters ( >170 nm), force modulation micro...

of hereditary disorders characterized by mechanical stress-induced blistering of the skin, which results from tissue separation within the epidermal basal keratinocytes (1). The most severe subtype is the Dowling-Meara type (EBS-DM); the moderately severe variant is other generalized (EBS, gen-nonDM) with generalized blister formation; and the mildest variant is localized with blistering confin...

A water-soluble poly(m-phenylene) bearing an achiral oligo(ethylene oxide) chain at the 5-position was synthesized by the Ni(0)-mediated homo-coupling polycondensation of a 3,5-dibromophenol monomer. The poly(m-phenylene) adopted a single helical conformation in protic media and self-assembled into a double helix in water through aromatic interaction, while it took a random-coil conformation in...

Two types of one-handed exact helical polymers, coil- and screw-shaped polymers, were synthesized by the two-point-covalent-linking protocol using C2-chiral spirobifluorene (SBF) and C2- or C(s)-symmetric anthraquinone spacers. Central to this protocol is a new aromatic ring-forming reaction based on the stepwise reductive cyclization of bis(aryloxy group)-substituted anthraquinone derivatives....

To examine whether helix formation necessarily precedes chain collision, we have measured the folding of a fully helical coiled coil that has been specially engineered to have negligible intrinsic helical propensity but high overall stability. The folding rate approaches the diffusion-limited value and is much faster than possible if folding is contingent on precollision helix formation. Theref...

Peptide TZ1H, based on the heptad sequence of a coiled-coil trimer, undergoes fully reversible, pH-dependent self-assembly into long-aspect-ratio helical fibers. Substitution of isoleucine residues with histidine at the core d-positions of alternate heptads introduces a mechanism by which self-assembly is coupled to the protonation state of the imidazole side chain. Circular dichroism spectrosc...

The design of dimeric coiled-coils has ultimately led to novel applications, such as self-replicating peptide systems, whereas the structural features of the less common trimeric coiled-coil continue to be elucidated. Novel topologies have been discovered in designed proteins, as exemplified by the right-handed tetrameric coiled-coil and the inverted U four-helix bundle, and a single switch of ...