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Title: Reactive Landing of Gramicidin S and Ubiquitin Ions onto Activated Self-Assembled Monolayer Surfaces

Abstract

Using mass-selected ion deposition combined with in situ infrared reflection absorption spectroscopy (IRRAS), we examined the reactive landing of gramicidin S and ubiquitin ions onto activated self-assembled monolayer (SAM) surfaces terminated with N-hydroxysuccinimidyl ester (NHS-SAM) and acyl fluoride (COF-SAM) groups. Doubly protonated gramicidin S, [GS+2H]2+, and two charge states of ubiquitin, [U+5H]5+ and [U+13H]13+, were used as model systems, allowing us to explore the effect of the number of free amino groups and the secondary structure on the efficiency of covalent bond formation between the projectile ion and the surface. For all projectile ions, ion deposition resulted in the depletion of IRRAS bands corresponding to the terminal groups on the SAM and the appearance of several new bands not associated with the deposited species. These new bands were assigned to the C=O stretching vibrations of COOH and COO- groups formed on the surface as a result of ion deposition. The presence of these bands was attributed to an alternative reactive landing pathway that competes with covalent bond formation. This pathway with similar yields for both gramicidin S and ubiquitin ions is analogous to the hydrolysis of the NHS ester bond in solution. The covalent bond formation efficiency increased linearly withmore » the number of free amino groups and was found to be lower for the more compact conformation of ubiquitin compared with the fully unfolded conformation. This observation was attributed to the limited availability of amino groups on the surface of the folded conformation. Our results have provided new insights on the efficiency and mechanism of reactive landing of peptides and proteins onto activated SAMs« less

Authors:
ORCiD logo;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1368115
Report Number(s):
PNNL-SA-123472
Journal ID: ISSN 1044-0305; 39717; KC0302020
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of the American Society for Mass Spectrometry; Journal Volume: 28; Journal Issue: 7
Country of Publication:
United States
Language:
English
Subject:
Environmental Molecular Sciences Laboratory

Citation Formats

Laskin, Julia, and Hu, Qichi. Reactive Landing of Gramicidin S and Ubiquitin Ions onto Activated Self-Assembled Monolayer Surfaces. United States: N. p., 2017. Web. doi:10.1007/s13361-017-1614-2.
Laskin, Julia, & Hu, Qichi. Reactive Landing of Gramicidin S and Ubiquitin Ions onto Activated Self-Assembled Monolayer Surfaces. United States. doi:10.1007/s13361-017-1614-2.
Laskin, Julia, and Hu, Qichi. Mon . "Reactive Landing of Gramicidin S and Ubiquitin Ions onto Activated Self-Assembled Monolayer Surfaces". United States. doi:10.1007/s13361-017-1614-2.
@article{osti_1368115,
title = {Reactive Landing of Gramicidin S and Ubiquitin Ions onto Activated Self-Assembled Monolayer Surfaces},
author = {Laskin, Julia and Hu, Qichi},
abstractNote = {Using mass-selected ion deposition combined with in situ infrared reflection absorption spectroscopy (IRRAS), we examined the reactive landing of gramicidin S and ubiquitin ions onto activated self-assembled monolayer (SAM) surfaces terminated with N-hydroxysuccinimidyl ester (NHS-SAM) and acyl fluoride (COF-SAM) groups. Doubly protonated gramicidin S, [GS+2H]2+, and two charge states of ubiquitin, [U+5H]5+ and [U+13H]13+, were used as model systems, allowing us to explore the effect of the number of free amino groups and the secondary structure on the efficiency of covalent bond formation between the projectile ion and the surface. For all projectile ions, ion deposition resulted in the depletion of IRRAS bands corresponding to the terminal groups on the SAM and the appearance of several new bands not associated with the deposited species. These new bands were assigned to the C=O stretching vibrations of COOH and COO- groups formed on the surface as a result of ion deposition. The presence of these bands was attributed to an alternative reactive landing pathway that competes with covalent bond formation. This pathway with similar yields for both gramicidin S and ubiquitin ions is analogous to the hydrolysis of the NHS ester bond in solution. The covalent bond formation efficiency increased linearly with the number of free amino groups and was found to be lower for the more compact conformation of ubiquitin compared with the fully unfolded conformation. This observation was attributed to the limited availability of amino groups on the surface of the folded conformation. Our results have provided new insights on the efficiency and mechanism of reactive landing of peptides and proteins onto activated SAMs},
doi = {10.1007/s13361-017-1614-2},
journal = {Journal of the American Society for Mass Spectrometry},
number = 7,
volume = 28,
place = {United States},
year = {Mon Mar 13 00:00:00 EDT 2017},
month = {Mon Mar 13 00:00:00 EDT 2017}
}