scholarly journals Effects of Amino Acid Side Chain Length and Chemical Structure on Anionic Polyglutamic and Polyaspartic Acid Cellulose-Based Polyelectrolyte Brushes

2021 ◽  
Author(s):  
Dmitry Tolmachev ◽  
George Mamistvalov ◽  
Natalia Lukasheva ◽  
Sergey Larin ◽  
Mikko Karttunen
Keyword(s):  
Glutamic Acid ◽  
Chain Length ◽  
Chemical Structure ◽  
Side Chain ◽  
Side Chains ◽  
Side Chain Length ◽  
Polyelectrolyte Brushes ◽  
Grafting Density ◽  
The Difference ◽  
Cellulose Surface

We used atomistic molecular dynamics (MD) simulations to study polyelectrolyte brushes based on anionic α-L-glutamic acid and α-L-aspartic acid grafted on cellulose in the presence of divalent CaCl2 salt at different concentrations. The motivation is the search of the ways to control properties such as sorption capacity and the structural response of the brush to multivalent salts. For this detailed understanding of the role of side chain length, chemical structure and their interplay is required. It was found that in the case of glutamic acid oligomers, the longer side chains facilitate attractive interactions with the cellulose surface, which forces the grafted chains to lie down on the surface. The additional methylene group in the side chain enables side chain rotation enhancing this effect. On the other hand, the shorter and more restricted side chains of aspartic acid oligomers prevent attractive interactions to a large degree and push the grafted chains away from the surface. The difference in side chain length also leads to differences in other properties of the brush in divalent salt solutions. At a low grafting density, the longer side chains of glutamic acid allow the adsorbed cations to be spatially distributed inside the brush resulting in a charge inversion. With an increase in grafting density, the difference in the total charge of the aspartic and glutamine brushes disappears, but new structural features appear. The longer sides allow for ion bridging between the grafted chains and the cellulose surface without a significant change in main chain conformation. This leads to the brush structure being less sensitive to changes in salt concentration.

scholarly journals Effects of Amino Acid Side-Chain Length and Chemical Structure on Anionic Polyglutamic and Polyaspartic Acid Cellulose-Based Polyelectrolyte Brushes

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1789
Author(s):  
Dmitry Tolmachev ◽  
George Mamistvalov ◽  
Natalia Lukasheva ◽  
Sergey Larin ◽  
Mikko Karttunen
Keyword(s):  
Glutamic Acid ◽  
Chain Length ◽  
Chemical Structure ◽  
Side Chain ◽  
Side Chains ◽  
Side Chain Length ◽  
Polyelectrolyte Brushes ◽  
Grafting Density ◽  
The Difference ◽  
Cellulose Surface

We used atomistic molecular dynamics (MD) simulations to study polyelectrolyte brushes based on anionic α,L-glutamic acid and α,L-aspartic acid grafted on cellulose in the presence of divalent CaCl2 salt at different concentrations. The motivation is to search for ways to control properties such as sorption capacity and the structural response of the brush to multivalent salts. For this detailed understanding of the role of side-chain length, the chemical structure and their interplay are required. It was found that in the case of glutamic acid oligomers, the longer side chains facilitate attractive interactions with the cellulose surface, which forces the grafted chains to lie down on the surface. The additional methylene group in the side chain enables side-chain rotation, enhancing this effect. On the other hand, the shorter and more restricted side chains of aspartic acid oligomers prevent attractive interactions to a large degree and push the grafted chains away from the surface. The difference in side-chain length also leads to differences in other properties of the brush in divalent salt solutions. At a low grafting density, the longer side chains of glutamic acid allow the adsorbed cations to be spatially distributed inside the brush resulting in a charge inversion. With an increase in grafting density, the difference in the total charge of the aspartic and glutamine brushes disappears, but new structural features appear. The longer sides allow for ion bridging between the grafted chains and the cellulose surface without a significant change in main-chain conformation. This leads to the brush structure being less sensitive to changes in salt concentration.

scholarly journals Percolation Phase Transition from Ionic Liquids to Ionic Liquid Crystals

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Shen Li ◽  
Yanting Wang
Keyword(s):  
Phase Transition ◽  
Ionic Liquid ◽  
Ionic Liquids ◽  
Chain Length ◽  
Complex Fluids ◽  
Dynamics Simulation ◽  
Coarse Grained ◽  
Side Chain ◽  
Side Chains ◽  
Side Chain Length

Abstract Due to their complex molecular structures and interactions, phase behaviors of complex fluids are quite often difficult to be identified by common phase transition analysis methods. Percolation phase transition, on the other hand, only monitors the degree of connection among particles without strict geometric requirements such as translational or orientational order, and thus suitable for pinpointing phase transitions of complex fluids. As typical complex fluids, ionic liquids (ILs) exhibit phases beyond the description of simple liquid theories. In particular, with an intermediate cationic side-chain length, ILs can form the nanoscale segregated liquid (NSL) state, which will eventually transform into the ionic liquid crystal (ILC) structure when the side chains are adequately long. However, the microscopic mechanism of this transformation is still unclear. In this work, by means of coarse-grained molecular dynamics simulation, we show that, with increasing cationic side-chain length, some local pieces of non-polar domains are gradually formed by side chains aligned in parallel inside the NSL phase, before an abrupt percolation phase transition happens when the system transforms into the ILC phase. This work not only identifies that the NSL to ILC phase transition is a critical phenomenon, but also demonstrates the importance of percolation theory to complex fluids.

scholarly journals Peptide/Peptoid Hybrid Oligomers: The Influence of Hydrophobicity and Relative Side-Chain Length on Antibacterial Activity and Cell Selectivity

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4429 ◽  
Author(s):  
Nicki Frederiksen ◽  
Paul R. Hansen ◽  
Fredrik Björkling ◽  
Henrik Franzyk
Keyword(s):  
Antibacterial Activity ◽  
Chain Length ◽  
Hydrophobic Surface ◽  
Structural Features ◽  
Side Chain ◽  
Side Chains ◽  
Side Chain Length ◽  
E Coli ◽  
Cell Selectivity ◽  
Wide Range

Previous optimisation studies of peptide/peptoid hybrids typically comprise comparison of structurally related analogues displaying different oligomer length and diverse side chains. The present work concerns a systematically constructed series of 16 closely related 12-mer oligomers with an alternating cationic/hydrophobic design, representing a wide range of hydrophobicity and differences in relative side-chain lengths. The aim was to explore and rationalise the structure–activity relationships within a subclass of oligomers displaying variation of three structural features: (i) cationic side-chain length, (ii) hydrophobic side-chain length, and (iii) type of residue that is of a flexible peptoid nature. Increased side-chain length of cationic residues led to reduced hydrophobicity till the side chains became more extended than the aromatic/hydrophobic side chains, at which point hydrophobicity increased slightly. Evaluation of antibacterial activity revealed that analogues with lowest hydrophobicity exhibited reduced activity against E. coli, while oligomers with the shortest cationic side chains were most potent against P. aeruginosa. Thus, membrane-disruptive interaction with P. aeruginosa appears to be promoted by a hydrophobic surface of the oligomers (comprised of the aromatic groups shielding the cationic side chains). Peptidomimetics with short cationic side chains exhibit increased hemolytic properties as well as give rise to decreased HepG2 (hepatoblastoma G2 cell line) cell viability. An optimal hydrophobicity window could be defined by a threshold of minimal hydrophobicity conferring activity toward E. coli and a threshold for maximal hydrophobicity, beyond which cell selectivity was lost.

Effects of side chains of oxatub[4]arene on its conformational interconversion, molecular recognition and macroscopic self-assembly

2017 ◽  
Vol 53 (93) ◽  
pp. 12572-12575 ◽  
Author(s):  
Liu-Pan Yang ◽  
Fei Jia ◽  
Fangfang Pan ◽  
Zhi-Sheng Pan ◽  
Kari Rissanen ◽  
...  
Keyword(s):  
Molecular Recognition ◽  
Chain Length ◽  
Self Assembly ◽  
Side Chain ◽  
Side Chains ◽  
Side Chain Length ◽  
Conformational Interconversion ◽  
Assembly Behavior

The side-chain length of oxatub[4]arenes was shown to affect its conformational interconversion, molecular recognition and macroscopic self-assembly behavior.

scholarly journals Hyperglutamylation of Tubulin Can either Stabilize or Destabilize Microtubules in the Same Cell

2009 ◽  
Vol 9 (1) ◽  
pp. 184-193 ◽  
Author(s):  
Dorota Wloga ◽  
Drashti Dave ◽  
Jennifer Meagley ◽  
Krzysztof Rogowski ◽  
Maria Jerka-Dziadosz ◽  
...  
Keyword(s):  
Chain Length ◽  
Eukaryotic Cells ◽  
Side Chain ◽  
Side Chains ◽  
Primary Sequence ◽  
Side Chain Length ◽  
Length Regulation ◽  
Cytoplasmic Microtubules

ABSTRACT In most eukaryotic cells, tubulin is subjected to posttranslational glutamylation, a conserved modification of unclear function. The glutamyl side chains form as branches of the primary sequence glutamic acids in two biochemically distinct steps: initiation and elongation. The length of the glutamyl side chain is spatially controlled and microtubule type specific. Here, we probe the significance of the glutamyl side chain length regulation in vivo by overexpressing a potent side chain elongase enzyme, Ttll6Ap, in Tetrahymena. Overexpression of Ttll6Ap caused hyperelongation of glutamyl side chains on the tubulin of axonemal, cortical, and cytoplasmic microtubules. Strikingly, in the same cell, hyperelongation of glutamyl side chains stabilized cytoplasmic microtubules and destabilized axonemal microtubules. Our observations suggest that the cellular outcomes of glutamylation are mediated by spatially restricted tubulin interactors of diverse nature.

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