Effect of Sequence on the Ionization Behavior of a Series of Amphiphilic Polypeptides

Langmuir ◽  
2013 ◽  
Vol 29 (14) ◽  
pp. 4451-4459 ◽  
Author(s):  
Michael Fowler ◽  
Bushra Siddique ◽  
Jean Duhamel
Keyword(s):  
Ionization Behavior

Ionization Behavior of Acidic Residues in Calbindin D9k

1999 ◽  
Vol 37 (1) ◽  
pp. 106-115 ◽  
Author(s):  
T�nu Kesvatera ◽  
Bo J�nsson ◽  
Eva Thulin ◽  
Sara Linse
Keyword(s):  
Calbindin D9k ◽  
Acidic Residues ◽  
Ionization Behavior

Ionization Behavior of Chitosan and Chitosan–DNA Polyplexes Indicate That Chitosan Has a Similar Capability to Induce a Proton-Sponge Effect as PEI

2013 ◽  
Vol 14 (6) ◽  
pp. 1732-1740 ◽  
Author(s):  
Isabelle Richard ◽  
Marc Thibault ◽  
Gregory De Crescenzo ◽  
Michael D. Buschmann ◽  
Marc Lavertu
Keyword(s):  
Proton Sponge ◽  
Ionization Behavior

scholarly journals Molecular Characterization, Antioxidant and Protein Solubility-Related Properties of Polyphenolic Compounds from Walnut (Juglans regia)

2016 ◽  
Vol 11 (5) ◽  
pp. 1934578X1601100 ◽  
Author(s):  
Diana Labuckas ◽  
Damián Maestri ◽  
Alicia Lamarque
Keyword(s):  
Phenolic Compounds ◽  
Molecular Characterization ◽  
Juglans Regia ◽  
Protein Solubility ◽  
Radical Scavenging ◽  
Analytical Techniques ◽  
Hydrogen Atom Transfer ◽  
Polyphenolic Compounds ◽  
Oh Groups ◽  
Ionization Behavior

Aqueous ethanol extraction of partially defatted walnut flours provides a simple and reliable method to obtain extracts with high content of polyphenolic compounds. These were characterized by means of HPLC-ESI-MS/MS analytical techniques and molecular parameters. Considering the whole set of polyphenolic compounds identified, a high average number of phenolic-OH groups was found. Although these represent potential hydrogen-atom transfer sites, which are associated with high free-radical scavenging capacity, results show that such a property could be strongly limited by the low lipophilicity of polyphenols affecting the accessibility of these molecules to lipid substrates. Variations in pH values were found to change the ionization behavior of phenolic compounds. These changes, however, had minor effects on walnut protein solubility-related properties. The results obtained in this study highlight the importance of molecular characterization of walnut phenolic compounds in order to assess better their bioactive properties.

scholarly journals Ionization behavior of nanoporous polyamide membranes

2020 ◽  
Vol 117 (48) ◽  
pp. 30191-30200
Author(s):  
Cody L. Ritt ◽  
Jay R. Werber ◽  
Mengyi Wang ◽  
Zhongyue Yang ◽  
Yumeng Zhao ◽  
...  
Keyword(s):  
High Performance ◽  
Interfacial Polymerization ◽  
Carboxyl Groups ◽  
Structure Property ◽  
Nanoconfined Water ◽  
Fundamental Understanding ◽  
Ionization Behavior ◽  
Water Salt ◽  
Low Permittivity ◽  
Polyamide Membranes

Escalating global water scarcity necessitates high-performance desalination membranes, for which fundamental understanding of structure–property–performance relationships is required. In this study, we comprehensively assess the ionization behavior of nanoporous polyamide selective layers in state-of-the-art nanofiltration (NF) membranes. In these films, residual carboxylic acids and amines influence permeability and selectivity by imparting hydrophilicity and ionizable moieties that can exclude coions. We utilize layered interfacial polymerization to prepare physically and chemically similar selective layers of controlled thickness. We then demonstrate location-dependent ionization of carboxyl groups in NF polyamide films. Specifically, only surface carboxyl groups ionize under neutral pH, whereas interior carboxyl ionization requires pH >9. Conversely, amine ionization behaves invariably across the film. First-principles simulations reveal that the low permittivity of nanoconfined water drives the anomalous carboxyl ionization behavior. Furthermore, we report that interior carboxyl ionization could improve the water–salt permselectivity of NF membranes over fourfold, suggesting that interior charge density could be an important tool to enhance the selectivity of polyamide membranes. Our findings highlight the influence of nanoconfinement on membrane transport properties and provide enhanced fundamental understanding of ionization that could enable novel membrane design.

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