Beyond Charge Density Matching: The Role of C–H···O Interactions in the Formation of Templated Vanadium Tellurites

2011 ◽  
Vol 11 (9) ◽  
pp. 4213-4219 ◽  
Author(s):  
Matthew D. Smith ◽  
Samuel M. Blau ◽  
Kelvin B. Chang ◽  
Matthias Zeller ◽  
Joshua Schrier ◽  
...  
Keyword(s):  
Charge Density

scholarly journals Deciphering the Role of π-Interactions in Polyelectrolyte Complexes Using Rationally Designed Peptides

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2074
Author(s):  
Sara Tabandeh ◽  
Cristina Elisabeth Lemus ◽  
Lorraine Leon
Keyword(s):  
Hydrogen Bonding ◽  
Phase Separation ◽  
Liquid Phase ◽  
Charge Density ◽  
Secondary Structures ◽  
Liquid Phase Separation ◽  
Polyelectrolyte Complexes ◽  
Π Interactions ◽  
Liquid Liquid Phase Separation

Electrostatic interactions, and specifically π-interactions play a significant role in the liquid-liquid phase separation of proteins and formation of membraneless organelles/or biological condensates. Sequence patterning of peptides allows creating protein-like structures and controlling the chemistry and interactions of the mimetic molecules. A library of oppositely charged polypeptides was designed and synthesized to investigate the role of π-interactions on phase separation and secondary structures of polyelectrolyte complexes. Phenylalanine was chosen as the π-containing residue and was used together with lysine or glutamic acid in the design of positively or negatively charged sequences. The effect of charge density and also the substitution of fluorine on the phenylalanine ring, known to disrupt π-interactions, were investigated. Characterization analysis using MALDI-TOF mass spectroscopy, H NMR, and circular dichroism (CD) confirmed the molecular structure and chiral pattern of peptide sequences. Despite an alternating sequence of chirality previously shown to promote liquid-liquid phase separation, complexes appeared as solid precipitates, suggesting strong interactions between the sequence pairs. The secondary structures of sequence pairs showed the formation of hydrogen-bonded structures with a β-sheet signal in FTIR spectroscopy. The presence of fluorine decreased hydrogen bonding due to its inhibitory effect on π-interactions. π-interactions resulted in enhanced stability of complexes against salt, and higher critical salt concentrations for complexes with more π-containing amino acids. Furthermore, UV-vis spectroscopy showed that sequences containing π-interactions and increased charge density encapsulated a small charged molecule with π-bonds with high efficiency. These findings highlight the interplay between ionic, hydrophobic, hydrogen bonding, and π-interactions in polyelectrolyte complex formation and enhance our understanding of phase separation phenomena in protein-like structures.

Charge Density Analysis of 2-Pyridineformamide N(4)-Methylthiosemicarbazone (Z′ = 4): Role of an Enhanced N–H···S Thioureido Dimer

2017 ◽  
Vol 17 (6) ◽  
pp. 2993-3004 ◽  
Author(s):  
Bojana M. Francuski ◽  
Sladjana B. Novaković ◽  
Djordje D. Francuski ◽  
Goran A. Bogdanović
Keyword(s):  
Charge Density ◽  
Density Analysis

scholarly journals Controlled Two-Dimensional Ferromagnetism in 1T–CrTe2: The Role of Charge Density Wave and Strain

2020 ◽  
Vol 124 (38) ◽  
pp. 21047-21053 ◽  
Author(s):  
Adolfo Otero Fumega ◽  
Jan Phillips ◽  
Victor Pardo
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Density Wave ◽  
Two Dimensional
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