The most commonly considered types of disorder in a crystal containing long-&& molecules are those in which the individual chain molecules are either rotated about their long axes or else translated along the fibre axis. However, since many fibrous polymers are helical in structure, we should also expect the possibility of screw disorder; that is, a combination of the above two types. A disorde...

We present an approach for designing self-assembled nanostructures from naturally occurring building block segments obtained from native protein structures. We focus on structural motifs from left-handed beta-helical proteins. We selected 17 motifs. Copies of each of the motifs are stacked one atop the other. The obtained structures were simulated for long periods by using Molecular Dynamics to...

A technique has been developed to fabricate polymeric helices with sub-micron dimensions. These helices are made using a double-templating process, in which an inorganic thin film deposited using glancing angle deposition acts as the master. The shape, pitch, handedness and number of turns of the polymer helices can be tuned by altering the deposition parameters of the master film. The structur...

While Amoeba proteus has long been the subject of extensive cytological and cytochemical studies, investigations with the electron microscope have been limited principally to the nuclear membrane (1-3). The observations reported herein were made in the course of studies intended to correlate cytochemistry (4) with knowledge of fine structure obtained with the electron microscope. I t is felt th...

Optically active, amphiphilic poly(meta-phenylene ethynylene)s (PPEa) bearing L- or D-alanine-derived oligo(ethylene glycol) side chains connected to the backbone via amide linkages were prepared by microwave-assisted polycondensation. PPEa's exhibited an intense Cotton effect in the π-conjugated main-chain chromophore regions in various polar and nonpolar organic solvents due to a predominantl...

In addition to conventional planar and helical flagellar waves, insect sperm flagella have also been observed to display a double-wave structure characterized by the presence of two superimposed helical waves. In this paper, we present a hydrodynamic investigation of the locomotion of insect spermatozoa exhibiting the double-wave structure, idealized here as superhelical waves. Resolving the hy...

Helical junctions are important elements in the architecture of folded RNA molecules. The global geometry of fully base-paired four-way junctions between RNA helices has been analyzed by comparative gel electrophoresis. Junctions appear to fold by pairwise coaxial helical stacking in one of two possible stereochemically equivalent isomers based upon alternative selections of stacking partners. ...

RecA family proteins, including bacterial RecA, archaeal RadA, and eukaryotic Dmc1 and Rad51, mediate homologous recombination, a reaction essential for maintaining genome integrity. In the presence of ATP, these proteins bind a single-strand DNA to form a right-handed nucleoprotein filament, which catalyzes pairing and strand exchange with a homologous double-stranded DNA (dsDNA), by as-yet un...

Although Fourier transform (FT) and tryptophan-scanning mutagenesis (TrpScanM) have been extremely useful for predicting secondary structures of membrane proteins, they are deemed to be low-resolution techniques. Herein, we describe the combined use of FT and TrpScanM (FT-TrpScanM) as a more reliable approach for the prediction of secondary structure. Five TrpScanM studies of the acetylcholine ...