scholarly journals Understanding Proton Transfer in Non-aqueous Biopolymers based on Helical Peptides: A Quantum Mechanical Study

2022 ◽  
Author(s):  
Jiang Bian ◽  
Anthony Cruz ◽  
Gabriel Lopez-Morales ◽  
Anton Kyrylenko ◽  
Donna McGregor ◽  
...  
Keyword(s):  
Proton Transfer ◽  
Proton Affinity ◽  
Vibrational Energy ◽  
Zero Point ◽  
Proton Donor ◽  
Ab Initio Molecular Dynamics ◽  
Helical Peptides ◽  
Point Energy ◽  
High Proton Affinity ◽  
High Proton

Histidine (an imidazole-based amino acid) is a promising building block for short aromatic peptides containing a proton donor/acceptor moiety. Previous studies have shown that polyalanine helical peptides substituted at regular intervals with histidine residues exhibit both structural stability as well as high proton affinity and high conductivity. Here, we present first-principle calculations of non-aqueous histidine-containing 310-,  and -helices and show that they are able to form hydrogen-bonded networks mimicking proton wires that have the ability to shuttle protons via the Grotthuss shuttling mechanism. The formation of these wires enhances the stability of the helices, and our structural characterizations confirm that the secondary structures are conserved despite distortions of the backbones. In all cases, the helices exhibit high proton affinity and proton transfer barriers on the order of 1~4 kcal/mol. Zero-point energy calculations suggest that for these systems, ground state vibrational energy can provide enough energy to cross the proton transport energy barrier. Additionally, ab initio molecular dynamics results suggests that the protons are transported unidirectionally through the wire at a rate of approximately 2 Å every 20 fs. These results demonstrate that efficient deprotonation-controlled proton wires can be formed using non-aqueous histidine-containing helical peptides.

scholarly journals ESI-MS spectra of 3-cyano-4-(substituted phenyl)-6-phenyl-2(1H)-pyridinones

2009 ◽  
Vol 74 (3) ◽  
pp. 223-235
Author(s):  
Aleksandar Marinkovic ◽  
Tatjana Vasiljevic ◽  
Mila Lausevic ◽  
Bratislav Jovanovic
Keyword(s):  
Proton Affinity ◽  
Phenyl Ring ◽  
Steric Effect ◽  
Proton Acceptor ◽  
Tandem Mass ◽  
High Proton Affinity ◽  
High Proton ◽  
Negative Electrospray Ionization ◽  
Cn Radicals ◽  
Fragmentation Processes

Twelve 3-cyano-4-(substituted phenyl)-6-phenyl-2(1H)-pyridinones were investigated by tandem mass spectrometry using positive as well as negative electrospray ionization. The influence of the electron affinity of the substituent and the steric effect on the fragmentation is discussed. Pyridinones with a substituent of low proton affinity show loss of water, HCN or benzene from the pyridinone ring in the first step of MS2 fragmentations. Oppositely, if a substituent with high proton affinity is present on the phenyl ring in the 4-position of pyridinone, the fragmentation paths are complex, depending mainly on the substituent proton acceptor ability. Elimination of neutral molecules CO, HCN, H2O, PhH (benzene) or Ph and CN radicals are fragmentation processes common for all compounds in the subsequent steps of the fragmentations.

Effect of anion reorientation on proton mobility in the solid acids family CsHyXO4 (X = S, P, Se, y = 1, 2) from ab initio molecular dynamics simulations

2020 ◽  
Vol 22 (19) ◽  
pp. 10738-10752 ◽  
Author(s):  
Christian Dreßler ◽  
Daniel Sebastiani
Keyword(s):  
Molecular Dynamics ◽  
High Temperature ◽  
Proton Transfer ◽  
Ab Initio ◽  
Solid Acids ◽  
Ab Initio Molecular Dynamics ◽  
Proton Mobility ◽  
Transfer Rates ◽  
High Proton ◽  
Dynamics Simulations

The high temperature phases of the solid acids CsHSeO4, CsHSO4 and CsH2PO4 show extraordinary high proton conductivities, which are enabled by the interplay of high proton transfer rates and frequent anion reorientation.

scholarly journals Improving peptide fragmentation by N-terminal derivatization with high proton affinity

2011 ◽  
Vol 25 (9) ◽  
pp. 1130-1140 ◽  
Author(s):  
Masahiro Miyashita ◽  
Yosuke Hanai ◽  
Hiroyuki Awane ◽  
Toru Yoshikawa ◽  
Hisashi Miyagawa
Keyword(s):  
Proton Affinity ◽  
Peptide Fragmentation ◽  
High Proton Affinity ◽  
High Proton

Exploring zero-point energies and hydrogen bond geometries along proton transfer pathways by low-temperature NMR

1999 ◽  
Vol 77 (5-6) ◽  
pp. 943-949 ◽  
Author(s):  
Sergei N Smirnov ◽  
Hans Benedict ◽  
Nikolai S Golubev ◽  
Gleb S Denisov ◽  
Maurice M Kreevoy ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Chemical Shift ◽  
Proton Transfer ◽  
Isotopic Fractionation ◽  
Zero Point ◽  
Strong Hydrogen Bond ◽  
Zero Point Energy ◽  
Acid Base ◽  
Point Energy ◽  
Fractionation Factors

We have followed by NMR the zero-point energy changes of the hydrogen bond proton in 1:1 acid-base complexes AHB triple bond {A—H···B <-–> Aδ-···H···Bδ+ <-–> A-···H—B+} as a function of the proton position between A and B. For this purpose, the isotopic fractionation factors K between the acid-base complexes AHB + Ph3COD···B –><- ADB + Ph3COH···B, where AH represents a variety of acids and B represents pyridine-15N, were measured around 110 K, using a 2:1 mixture of liquefied CDClF2-CDF3 as solvent. As under these conditions the slow hydrogen bond exchange regime is reached, the values of K could be obtained directly by integration of appropriate proton NMR signals. Using the valence-bond order concept established previously by crystallography, the fractionation factors and corresponding zero-point energy changes (ΔZPE) are related in a quantitative way to the hydrogen bond geometries, the 1H chemical shift of the hydrogen bond proton, and the pyridine-15N chemical shift. The K values are related in a quasi-linear way to the chemical shifts of the hydrogen bond proton, where the slope depends on whether the proton is closer to oxygen or nitrogen. In the region of the strongly hydrogen-bonded quasi-symmetric complexes, which are characterized by a strong hydrogen bond contraction, the variation of K is very small in spite of substantial proton displacements.Key words: NMR, isotopic fractionation, hydrogen bonding, acid-base complexes, proton transfer, geometric isotope effects.

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