Dynamics of a Probe Molecule Dissolved in Several Polymer Matrices with Different Side-Chain Structures: Determination of Correlation Length Relevant to Glass Transition

2013 ◽  
Vol 46 (6) ◽  
pp. 2206-2215 ◽  
Author(s):  
Shogo Nobukawa ◽  
Osamu Urakawa ◽  
Toshiyuki Shikata ◽  
Tadashi Inoue
Keyword(s):  
Glass Transition ◽  
Correlation Length ◽  
Polymer Matrices ◽  
Probe Molecule ◽  
Side Chain

Polypeptides Folding: Rules for the Calculation of the Backbone Dihedral Angles φ starting from the Amino Acid Sequence

2020 ◽  
Author(s):  
Michele Larocca
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Theoretical Approach ◽  
Polypeptide Chain ◽  
Hydrophobic Effect ◽  
Side Chain ◽  
Dihedral Angles ◽  
Mechanical Forces ◽  
Specific Chemical

<p>Protein folding is strictly related to the determination of the backbone dihedral angles and depends on the information contained in the amino acid sequence as well as on the hydrophobic effect. To date, the type of information embedded in the amino acid sequence has not yet been revealed. The present study deals with these problematics and aims to furnish a possible explanation of the information contained in the amino acid sequence, showing and reporting rules to calculate the backbone dihedral angles φ. The study is based on the development of mechanical forces once specific chemical interactions are established among the side chain of the residues in a polypeptide chain. It aims to furnish a theoretical approach to predict backbone dihedral angles which, in the future, may be applied to computational developments focused on the prediction of polypeptide structures.</p>

scholarly journals Gating Competence of Constitutively Open CLC-0 Mutants Revealed by the Interaction with a Small Organic Inhibitor

2003 ◽  
Vol 122 (3) ◽  
pp. 295-306 ◽  
Author(s):  
Sonia Traverso ◽  
Laura Elia ◽  
Michael Pusch
Keyword(s):  
Chloride Channels ◽  
Bound State ◽  
Side Chain ◽  
Pore Channel ◽  
Kinetic Properties ◽  
Wild Type ◽  
High Affinity ◽  
Critical Residue ◽  
Fast Gating

Opening of CLC chloride channels is coupled to the translocation of the permeant anion. From the recent structure determination of bacterial CLC proteins in the closed and open configuration, a glutamate residue was hypothesized to form part of the Cl−-sensitive gate. The negatively charged side-chain of the glutamate was suggested to occlude the permeation pathway in the closed state, while opening of a single protopore of the double-pore channel would reflect mainly a movement of this side-chain toward the extracellular pore vestibule, with little rearrangement of the rest of the channel. Here we show that mutating this critical residue (Glu166) in the prototype Torpedo CLC-0 to alanine, serine, or lysine leads to constitutively open channels, whereas a mutation to aspartate strongly slowed down opening. Furthermore, we investigated the interaction of the small organic channel blocker p-chlorophenoxy-acetic acid (CPA) with the mutants E166A and E166S. Both mutants were strongly inhibited by CPA at negative voltages with a &gt;200-fold larger affinity than for wild-type CLC-0 (apparent KD at −140 mV ∼4 μM). A three-state linear model with an open state, a low-affinity and a high-affinity CPA-bound state can quantitatively describe steady-state and kinetic properties of the CPA block. The parameters of the model and additional mutagenesis suggest that the high-affinity CPA-bound state is similar to the closed configuration of the protopore gate of wild-type CLC-0. In the E166A mutant the glutamate side chain that occludes the permeation pathway is absent. Thus, if gating consists only in movement of this side-chain the mutant E166A should not be able to assume a closed conformation. It may thus be that fast gating in CLC-0 is more complex than anticipated from the bacterial structures.

scholarly journals Hole-transporting side-chain polystyrenes based on TCTA with tuned glass transition and optimized electronic properties

RSC Advances ◽  
2015 ◽  
Vol 5 (101) ◽  
pp. 83122-83128 ◽  
Author(s):  
Felix R. P. Limberg ◽  
Arunas Miasojedovas ◽  
Patrick Pingel ◽  
Felix Reisbeck ◽  
Silvia Janietz ◽  
...  
Keyword(s):  
Glass Transition ◽  
Electronic Properties ◽  
Significant Influence ◽  
Life Time ◽  
Side Chain ◽  
Hole Transporting ◽  
Solution Processable

The development of crosslinkable materials for solution processable OLEDs presents challenges, especially regarding the adjustment of the glass transition, which has a significant influence on crosslinking kinetics and device life-time.

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