Bibliographic Details
| Title: |
Unimolecular dissociation of peptides: statistical vs. non-statistical fragmentation mechanisms and time scales. |
| Authors: |
Spezia R; Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement, CEA CNRS, Université Paris Saclay, 91025 Evry, France. riccardo.spezia@univ-evry.fr and LAMBE, Université d'Evry-Val-d'Essonne, 91025 Evry, France., Martin-Somer A; Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement, CEA CNRS, Université Paris Saclay, 91025 Evry, France. riccardo.spezia@univ-evry.fr and LAMBE, Université d'Evry-Val-d'Essonne, 91025 Evry, France., Macaluso V; Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement, CEA CNRS, Université Paris Saclay, 91025 Evry, France. riccardo.spezia@univ-evry.fr and LAMBE, Université d'Evry-Val-d'Essonne, 91025 Evry, France., Homayoon Z; Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, USA., Pratihar S; Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, USA., Hase WL; Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, USA. |
| Source: |
Faraday discussions [Faraday Discuss] 2016 Dec 22; Vol. 195, pp. 599-618. |
| Publication Type: |
Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, Non-U.S. Gov't |
| Language: |
English |
| Journal Info: |
Publisher: Faraday Division, Royal Society of Chemistry Country of Publication: England NLM ID: 9212301 Publication Model: Print Cited Medium: Internet ISSN: 1364-5498 (Electronic) Linking ISSN: 13596640 NLM ISO Abbreviation: Faraday Discuss Subsets: PubMed not MEDLINE |
| Imprint Name(s): |
Original Publication: London : Faraday Division, Royal Society of Chemistry, c1992- |
| Abstract: |
In the present work we have investigated mechanisms of gas phase unimolecular dissociation of a relatively simple dipeptide, the di-proline anion, by means of chemical dynamics simulations, using the PM3 semi-empirical Hamiltonian. In particular, we have considered two activation processes that are representative limits of what occurs in collision induced dissociation experiments: (i) thermal activation, corresponding to several low energy collisions, in which the system is prepared with a microcanonical distribution of energy; (ii) collisional activation where a single shock of hundreds of kcal mol-1 (300 kcal mol-1 in the present case) can transfer sufficient energy to allow dissociation. From these two activation processes we obtained different product abundances, and for one particular fragmentation pathway a clear mechanistic difference for the two activation processes. This mechanism corresponds to the leaving of an OH- group and subsequent formation of water by taking a proton from the remaining molecule. This last reaction is always observed in thermal activation while in collisional activation it is less favoured and the formation of OH- as a final product is observed. More importantly, we show that while in thermal activation unimolecular dissociation follows exponential decay, in collision activation the initial population decays with non-exponential behaviour. Finally, from the thermal activation simulations it was possible to obtain rate constants as a function of temperature that show Arrhenius behaviour. Thus activation energies have also been extracted from these simulations. |
| Entry Date(s): |
Date Created: 20161007 Date Completed: 20180718 Latest Revision: 20180718 |
| Update Code: |
20260130 |
| DOI: |
10.1039/c6fd00126b |
| PMID: |
27711796 |
| Database: |
MEDLINE |