scholarly journals Analysis of Fragmentation Pathways of Peptide Modified with Quaternary Ammonium and Phosphonium Group as Ionization Enhancers

Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 6964
Author(s):  
Monika Kijewska ◽  
Dorota Gąszczyk ◽  
Remigiusz Bąchor ◽  
Piotr Stefanowicz ◽  
Zbigniew Szewczuk
Keyword(s):  
Quaternary Ammonium ◽  
Positive Charge ◽  
Fixed Charge ◽  
Peptide Sequence ◽  
Peptide Conjugates ◽  
Fragmentation Pathways ◽  
Peptide Modification ◽  
Acid Effect ◽  
Quaternary Ammonium Group ◽  
Modified Peptides

Peptide modification by a quaternary ammonium group containing a permanent positive charge is a promising method of increasing the ionization efficiency of the analyzed compounds, making ultra-sensitive detection even at the attomolar level possible. Charge-derivatized peptides may undergo both charge remote (ChR) and charge-directed (ChD) fragmentation. A series of model peptide conjugates derivatized with N,N,N-triethyloammonium (TEA), 1-azoniabicyclo[2.2.2]octane (ABCO), 2,4,6-triphenylopyridinium (TPP) and tris(2,4,6-trimetoxyphenylo)phosphonium (TMPP) groups were analyzed by their fragmentation pathways both in collision-induced dissociation (CID) and electron-capture dissociation (ECD) mode. The effect of the fixed-charge tag type and peptide sequence on the fragmentation pathways was investigated. We found that the aspartic acid effect plays a crucial role in the CID fragmentation of TPP and TEA peptide conjugates whereas it was not resolved for the peptides derivatized with the phosphonium group. ECD spectra are mostly dominated by cn ions. ECD fragmentation of TMPP-modified peptides results in the formation of intense fragments derived from this fixed-charge tag, which may serve as reporter ion.

scholarly journals Quaternary Ammonium Chitosans: The Importance of the Positive Fixed Charge of the Drug Delivery Systems

2020 ◽  
Vol 21 (18) ◽  
pp. 6617 ◽  
Author(s):  
Angela Fabiano ◽  
Denise Beconcini ◽  
Chiara Migone ◽  
Anna Maria Piras ◽  
Ylenia Zambito
Keyword(s):  
Drug Delivery ◽  
Quaternary Ammonium ◽  
Drug Delivery Systems ◽  
Ex Vivo ◽  
Delivery Systems ◽  
Fixed Charge ◽  
Innovative Drug ◽  
Natural Polysaccharide ◽  
The Impact

As a natural polysaccharide, chitosan has good biocompatibility, biodegradability and biosecurity. The hydroxyl and amino groups present in its structure make it an extremely versatile and chemically modifiable material. In recent years, various synthetic strategies have been used to modify chitosan, mainly to solve the problem of its insolubility in neutral physiological fluids. Thus, derivatives with negative or positive fixed charge were synthesized and used to prepare innovative drug delivery systems. Positively charged conjugates showed improved properties compared to unmodified chitosan. In this review the main quaternary ammonium derivatives of chitosan will be considered, their preparation and their applications will be described to evaluate the impact of the positive fixed charge on the improvement of the properties of the drug delivery systems based on these polymers. Furthermore, the performances of the proposed systems resulting from in vitro and ex vivo experiments will be taken into consideration, with particular attention to cytotoxicity of systems, and their ability to promote drug absorption.

scholarly journals Crystal Structure of a Cationic Bile Salt Derivative ([3,5,7,12]-3-(2-naphthyloylamino)-7,12-dihydroxycholan-24-triethylammonium iodide)

Crystals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 135
Author(s):  
Francisco Meijide ◽  
María Pilar Vázquez-Tato ◽  
Julio Seijas ◽  
Santiago de Frutos ◽  
Juan V. Trillo Novo ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Quaternary Ammonium ◽  
Electrostatic Interactions ◽  
Amide Bond ◽  
Orthorhombic Space Group ◽  
Steroid Nucleus ◽  
Quaternary Ammonium Group ◽  
Group A ◽  
Hydroxy Groups

The crystal structure of the iodide salt of a quaternary ammonium derivative of cholic acid having a naphthalene group attached to the 3rd position of the steroid nucleus through an amide bond ([3,5,7,12]-3-(2-naphthyloylamino)-7,12-dihydroxycholan-24-triethylammonium iodide) has been resolved. The compound crystallizes in the P212121 orthorhombic space group (a/Å = 10.9458(3); b/Å = 12.1625(3); c/Å = 28.4706(7)). The lateral chain adopts a fully extended tttt conformation because the quaternary ammonium group cannot participate in the formation of hydrogen bonds. The iodide ion is involved in the formation of hydrogen bonds as well as the amide group and the two steroid hydroxy groups. Hirshfeld surface analysis confirms that these contacts, as well as the electrostatic interactions, stabilize the structure. The helixes around the 21 screw axis are right-handed ones.

A Highly Active Aqueous Olefin Metathesis Catalyst Bearing a Quaternary Ammonium Group

ChemSusChem ◽  
2008 ◽  
Vol 1 (1-2) ◽  
pp. 103-109 ◽  
Author(s):  
Łukasz Gułajski ◽  
Anna Michrowska ◽  
Joanna Narożnik ◽  
Zuzanna Kaczmarska ◽  
Leszek Rupnicki ◽  
...  
Keyword(s):  
Quaternary Ammonium ◽  
Olefin Metathesis ◽  
Ammonium Group ◽  
Highly Active ◽  
Metathesis Catalyst ◽  
Quaternary Ammonium Group

DE NOVO SEQUENCING WITH LIMITED NUMBER OF POST-TRANSLATIONAL MODIFICATIONS PER PEPTIDE

2013 ◽  
Vol 11 (04) ◽  
pp. 1350007 ◽  
Author(s):  
LIN HE ◽  
XI HAN ◽  
BIN MA
Keyword(s):  
De Novo ◽  
Search Space ◽  
De Novo Sequencing ◽  
Peptide Sequence ◽  
Post Translational Modification ◽  
Post Translational Modifications ◽  
Protein Databases ◽  
Sequencing Algorithm ◽  
Modified Peptides ◽  
Proteomics Research

De novo sequencing derives the peptide sequence from a tandem mass spectrum without the assistance of protein databases. This analysis has been indispensable for the identification of novel or modified peptides in a biological sample. Currently, the speed of de novo sequencing algorithms is not heavily affected by the number of post-translational modification (PTM) types in consideration. However, the accuracy of the algorithms can be degraded due to the increased search space. Most peptides in a proteomics research contain only a small number of PTMs per peptide, yet the types of PTMs can come from a large number of choices. Therefore, it is desirable to include a large number of PTM types in a de novo sequencing algorithm, yet to limit the number of PTM occurrences in each peptide to increase the accuracy. In this paper, we present an efficient de novo sequencing algorithm, DeNovoPTM, for such a purpose. The implemented software is downloadable from http://www.cs.uwaterloo.ca/~l22he/denovo_ptm .

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