Coiled coils are highly represented in biologically relevant macromolecules involved in important biological functions, such as gene expression regulation. The coiled coil environment has the great advantage to provide two very well defined intermolecular recognition surfaces. The peptide system VPE-VPK is a rationally designed heterodimeric coiled coil structure [1,2]. The characteristic struc...

We characterized the α-to-β transition in α-helical coiled-coil connectors of the human fibrin(ogen) molecule using biomolecular simulations of their forced elongation and theoretical modeling. The force (F)-extension (X) profiles show three distinct regimes: (1) the elastic regime, in which the coiled coils act as entropic springs (F < 100-125 pN; X < 7-8 nm); (2) the constant-force plastic re...

Inspired by the natural design of bacterial flagella, we report artificial bacterial flagella ABF that have a comparable shape and size to their organic counterparts and can swim in a controllable fashion using weak applied magnetic fields. The helical swimmer consists of a helical tail resembling the dimensions of a natural flagellum and a thin soft-magnetic “head” on one end. The swimming loc...

The dimerization of polyalanine peptides in a hydrophobic environment was explored using replica exchange molecular dynamics simulations. A nonpolar solvent (cyclohexane) was used to mimic, among other hydrophobic environments, the hydrophobic interior of a membrane in which the peptides are fully embedded. Our simulations reveal that while the polyalanine monomer preferentially adopts a beta-h...

The biological functions of coiled coils generally depend on efficient folding and perfect pairing of their α-helices. Dynamic changes in the helical registry that lead to staggered helices have only been proposed for a few special systems and not found in generic coiled coils. Here, we report our observations of multiple staggered helical structures of two canonical coiled coils. The partially...

Contractility in fibers can arise from changes of macromolecular conformation caused by changes in some thermodynamic variable such as temperature, pH, or solvent composition. Illustrations are given of contractile processes in fibers and of changes in macromolecular conformation in dilute solution. These may involve order-disorder transitions, e.g. of the type exhibited by the helix-coil trans...

The dimeric form of the kinesin motor and neck domain from rat brain with bound ADP has been solved by X-ray crystallography. The two heads of the dimer are connected via a coiled-coil alpha-helical interaction of their necks. They are broadly similar to one another; differences are most apparent in the head-neck junction and in a moderate reorientation of the neck helices in order to adopt to ...

The bacteriophage phi29 replication protein p1 self-interacts in vitro, generating highly ordered structures. Specifically, the 53-amino acid protein p1DeltaN33, which retains the sequence of p1 spanning amino acids Met(34) to Lys(85), assembles into two-dimensional protofilament sheets. The region of protein p1 located between residues Glu(38) and Asn(65) presumably forms an alpha-helical coil...

The analytical expression of the on-axis field for an infinitely long helical undulator, derived in terms of undulator period length, uniform current density, inner radius and dimensions of the coils, was compared with numerical analyses of model undulators based on the Biot-Savart law. The two calculations agreed within 110. The expression also showed that the on-axis field has the first harm...