Side chain packing states of chitosan‐based supramolecular derivatives containing long alkyl side chains

2020 ◽  
Vol 3 (2) ◽  
Author(s):  
Lingzhi Liu ◽  
Dong Lyu ◽  
Mingyue Xiang ◽  
Yongfeng Men
Keyword(s):  
Side Chain ◽  
Side Chains ◽  
Chain Packing ◽  
Alkyl Side Chains ◽  
Side Chain Packing

scholarly journals Too packed to change: site-specific substitution rates and side-chain packing in protein evolution

2014 ◽  
Author(s):  
María Laura Marcos ◽  
Julian Echave
Keyword(s):  
Protein Evolution ◽  
Packing Density ◽  
Main Chain ◽  
Side Chain ◽  
Side Chains ◽  
Contact Density ◽  
Chain Packing ◽  
Site Specific ◽  
Stress Theory ◽  
Side Chain Packing

In protein evolution, due to functional and biophysical constraints, the rates of amino acid substitution differ from site to site. Among the best predictors of site-specific rates is packing density. The packing density measure that best correlates with rates is the weighted contact number (WCN), the sum of inverse square distances between the site’s Cαand the other Cαs . According to a mechanistic stress model proposed recently, rates are determined by packing because mutating packed sites stresses and destabilizes the protein’s active conformation. While WCN is a measure of Cαpacking, mutations replace side chains, which prompted us to consider whether a site’s evolutionary divergence is constrained by main-chain packing or side-chain packing. To address this issue, we extended the stress theory to model side chains explicitly. The theory predicts that rates should depend solely on side-chain packing. We tested these predictions on a data set of structurally and functionally diverse monomeric enzymes. We found that, on average, side-chain contact density (WCNρ) explains 39.1% of among-sites rate variation, larger than main-chain contact density (WCNα) which explains 32.1%. More importantly, the independent contribution of WCNαis only 0.7%. Thus, as predicted by the stress theory, site-specific evolutionary rates are determined by side-chain packing.

scholarly journals Synthesis of New Derivatives of BEDT-TTF: Installation of Alkyl, Ethynyl, and Metal-Binding Side Chains and Formation of Tris(BEDT-TTF) Systems

2021 ◽  
Vol 7 (8) ◽  
pp. 110
Author(s):  
Songjie Yang ◽  
Matteo Zecchini ◽  
Andrew Brooks ◽  
Sara Krivickas ◽  
Desiree Dalligos ◽  
...  
Keyword(s):  
Metal Binding ◽  
Tricarboxylic Acid ◽  
Metal Salts ◽  
Side Chain ◽  
Side Chains ◽  
Ethynyl Group ◽  
X Ray ◽  
Transition Metal Salts ◽  
Alkyl Side Chains ◽  
Derivatives Of

The syntheses of new BEDT-TTF derivatives are described. These comprise BEDT-TTF with one ethynyl group (HC≡C-), with two (n-heptyl) or four (n-butyl) alkyl side chains, with two trans acetal (-CH(OMe)2) groups, with two trans aminomethyl (-CH2NH2) groups, and with an iminodiacetate (-CH2N(CH2CO2−)2 side chain. Three transition metal salts have been prepared from the latter donor, and their magnetic properties are reported. Three tris-donor systems are reported bearing three BEDT-TTF derivatives with ester links to a core derived from benzene-1,3,5-tricarboxylic acid. The stereochemistry and molecular structure of the donors are discussed. X-ray crystal structures of two BEDT-TTF donors are reported: one with two CH(OMe)2 groups and with one a -CH2N(CH2CO2Me)2 side chain.

scholarly journals Packing of apolar side chains enables accurate design of highly stable membrane proteins

Science ◽  
2019 ◽  
Vol 363 (6434) ◽  
pp. 1418-1423 ◽  
Author(s):  
Marco Mravic ◽  
Jessica L. Thomaston ◽  
Maxwell Tucker ◽  
Paige E. Solomon ◽  
Lijun Liu ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Hydrophobic Effect ◽  
Side Chain ◽  
Side Chains ◽  
Chain Packing ◽  
Membrane Protein Folding ◽  
Natural Protein ◽  
Accurate Design ◽  
Polar Interactions ◽  
Packing Code

The features that stabilize the structures of membrane proteins remain poorly understood. Polar interactions contribute modestly, and the hydrophobic effect contributes little to the energetics of apolar side-chain packing in membranes. Disruption of steric packing can destabilize the native folds of membrane proteins, but is packing alone sufficient to drive folding in lipids? If so, then membrane proteins stabilized by this feature should be readily designed and structurally characterized—yet this has not been achieved. Through simulation of the natural protein phospholamban and redesign of variants, we define a steric packing code underlying its assembly. Synthetic membrane proteins designed using this code and stabilized entirely by apolar side chains conform to the intended fold. Although highly stable, the steric complementarity required for their folding is surprisingly stringent. Structural informatics shows that the designed packing motif recurs across the proteome, emphasizing a prominent role for precise apolar packing in membrane protein folding, stabilization, and evolution.

scholarly journals Controlled steric selectivity in molecular doping towards closest-packed supramolecular conductors

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Shinya Kohno ◽  
Yu Yamashita ◽  
Naotaka Kasuya ◽  
Tsubasa Mikie ◽  
Itaru Osaka ◽  
...  
Keyword(s):  
Conjugated Polymers ◽  
Steric Effects ◽  
Side Chain ◽  
Side Chains ◽  
Void Space ◽  
Alkyl Side Chains ◽  
Recent Developments ◽  
High Carrier ◽  
Molecular Doping ◽  
Steric Selectivity

Abstract Recent developments in molecular doping technologies allow extremely high carrier densities in polymeric semiconductors, exhibiting great diversity because of the unique size, conformation, and steric effect of molecular dopants. However, it is controversial how steric effects can limit the doping efficiency and to what extent dopants can be accommodated in polymers. Here, we employ two distinct conjugated polymers with different alkyl side-chain densities, where polymers are doped via anion-change, allowing greater variation in the incorporation of molecular dopants having different electrostatic potentials and shapes. We characterize the doping efficiency with regard to steric effects, considering the unique void space in the conjugated polymers. Our study reveals that doping efficiency of polymers with sparse alkyl side-chains is significantly greater than that with dense side-chains. A closest-packed supramolecule is realized with a particular combination of a sparse polymer and a large dopant, giving rise to high conductivity, air stability, and remarkably high work function. This work provides a critical insight into overcoming steric effects in molecular doping.

n-Alkylresorcinol Occurrence in Mercurialis perennis L. (Euphorbiaceae)

2010 ◽  
Vol 65 (3-4) ◽  
pp. 174-179 ◽  
Author(s):  
Peter Lorenz ◽  
Matthias Knödler ◽  
Julia Bertrams ◽  
Melanie Berger ◽  
Ulrich Meyer ◽  
...  
Keyword(s):  
Side Chain ◽  
Side Chains ◽  
Alkyl Side Chain ◽  
Alkyl Side Chains ◽  
Chain Lengths ◽  
New View

Investigation of the dichloromethane extracts from herbal and root parts of Mercurialis perennis L. afforded a mixture of 11 homologous n-alkylresorcinols (ARs) with saturated odd-numbered alkyl side chains (C15:0-C27:0). In addition to three predominant ARs (C19:0, C21:0 and C23:0), a number of minor ARs were identified by use of LC-MS/MS and GC-MS techniques. Among the compounds detected, four uncommon ARs with evennumbered alkyl side chain lengths were also determined. The overall AR concentration in herbal parts was 7 to 9 times higher compared to that of the roots. The results presented may open a new view on the phytochemistry and pharmacognosy of M. perennis and other members of the Euphorbiaceae family.

Side Chain Packing of the N- and C-Terminal Helices Plays a Critical Role in the Kinetics of CytochromecFolding†

Biochemistry ◽  
1996 ◽  
Vol 35 (17) ◽  
pp. 5538-5549 ◽  
Author(s):  
Wilfredo Colón ◽  
Gülnur A. Elöve ◽  
L. Paul Wakem ◽  
Fred Sherman ◽  
Heinrich Roder
Keyword(s):  
Critical Role ◽  
Side Chain ◽  
Chain Packing ◽  
Kinetics Of ◽  
Side Chain Packing

Low band gap conjugated polymers combining siloxane-terminated side chains and alkyl side chains: side-chain engineering achieving a large active layer processing window for PCE > 10% in polymer solar cells

2017 ◽  
Vol 5 (33) ◽  
pp. 17619-17631 ◽  
Author(s):  
Xuncheng Liu ◽  
Li Nian ◽  
Ke Gao ◽  
Lianjie Zhang ◽  
Lechi Qing ◽  
...  
Keyword(s):  
Conjugated Polymers ◽  
Active Layer ◽  
Polymer Solar Cells ◽  
Hole Transport ◽  
Random Copolymers ◽  
Side Chain ◽  
Active Layer Thickness ◽  
Side Chains ◽  
Alkyl Side Chains ◽  
Thickness Tolerance

Side-chain random copolymers show high 3-D hole transport and offer excellent active layer thickness tolerance.

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