Oriented Helical Coils

Monera, O. D., Kay, C. M., and Hodges, R. S. (1994). Electrostatic interactions control the parallel and antiparallel orientation of alpha-helical chains in 2-stranded alpha-helical coiled-coils. Biochemistry 33, 3862-3871. 

Various theories have been introduced to explain the relative movemoit. Huxley proposed that the myosin head changed its orientation after binding to actin (die "rotating-head" model). According to the helix-coil transition, the normally o-helical coiled-coil structure "melts" to a random coil conformation, which implies a reduction in length. Movements of the myosin tails, as well as conformation changes of the actin have also been considered. It now seems clear, however, that the force production takes place in or very near the myosin heads [22]. Furthermore, among the three different states of myosin - empty actin site, ATP bound to the actin site and ADP-Pi boimd to die actin site - aU of which can... 

FTIR-ATR spectra of thin PAA-g-PEG or PEM-PEG films on metal substrates can be used to gain information about the structure as well as the areal density of EG units or PEG chains on the surface, if the films contain primarily randomly oriented or aligned helical coils. The analysis can be made for ultrathin layers with thicknesses down to a few nanometers, because the metal substrate will not cmitribute signals interfering with vibrational bands of the organic coating. Near the metal surface the electric field of the... 

Method A uses bulk ATR spectra of thick polycrystalline samples of PEG with a random orientation of helical coils Using the SpectraRay 2 software package (SENTECH Instruments GmbH, Berlin, Germany), Drude-Lorentz oscillator parameters [15] were determined by spectral line fits to selected vibrational bands of an ATR spectrum, taken from... 

Figure 3.S Schematic diagram of packing side chains In the hydrophobic core of colled-coll structures according to the "knobs In holes" model. The positions of the side chains along the surface of the cylindrical a helix Is pro-jected onto a plane parallel with the heUcal axis for both a helices of the coiled-coil. (a) Projected positions of side chains in helix 1. (b) Projected positions of side chains in helix 2. (c) Superposition of (a) and (b) using the relative orientation of the helices In the coiled-coil structure. The side-chain positions of the first helix, the "knobs," superimpose between the side-chain positions In the second helix, the "holes." The green shading outlines a d-resldue (leucine) from helix 1 surrounded by four side chains from helix 2, and the brown shading outlines an a-resldue (usually hydrophobic) from helix 1 surrounded by four side chains from helix 2.

In the case in which a helical product with a certain orientation of the single chains forms not only the maximum number, rmax, of hydrogen bonds - which means that the ends of the helical parts are coiled - the statistical weights are computed according to142 (Fig. 33) ... 

Figure 2.7 Structures of a lysine-specific hystone demethylase 1 (LSDl). In all three pictures, the LSDl protein is in the same orientation, (a) The human LSDl structure (PDB code 2HK0) with the tower domain (top two helices), just below the AOL domain, (harboring the FAD cofactor and the substrate-binding subdomain).The protein is represented schematically, with the helices, p-strands and coil regions colored in red, yellow and green, respectively. The FAD cofactor is in stick representation with the carbon, oxygen, phosphorus and nitrogen...

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