Author(s): Gomes, Anderson Herbert de Abreu, 1985- ; Brito, Arnaldo Naves de, 1962-
Date: 2019
Persistent ID: https://hdl.handle.net/20.500.12733/1664691
Origin: Oasisbr
Subject(s): Dinâmica; Aminoácidos; Fotoemissão; Energia; Nitrogênio; Dynamics; Aminoacids; Photoemission; Energy; Nitrogen; Artigo original
Agradecimentos: This research was supported by the Brazilian funding agencies CNPq (480967/2013-0), FAP-DF (193 140/95), and FINEP (1070/06). The Swedish–Brazilian collaboration STINT-CAPE (9805/2014-01). V.C. is grateful for the contribution from the Ministero della Istruzione della Universita’ e della Ricerca, Direzione Generale per la Internazionalizzazione della Ricerca of the Republic of Italy. H.Å. acknowledges support from the Swedish Science Research Council (6212012-3347). The authors gratefully acknowledge support from FAPESP (Sao Paulo Research Foundation, Process 2017/11986-5) and Shell and the strategic importance of the support given by ANP (Brazil’s National Oil, Natural Gas and Biofuels Agency) through the R&D levy regulation
Abstract: The distribution and protonation states of amino acids in water droplets are of considerable concern in studies on the formation of clouds in the atmosphere as well as in many biological contexts. In the present work we use the amino acid cysteine as a prototypical example and explore the protonation states of this molecule in aqueous solution, which are strongly affected by the acidity of the environment and also can show different distributions between surface and bulk. We use a combination of X-ray photoelectron chemical shift measurements, density functional theory calculations of the shifts, and reactive force field molecular dynamics simulations of the underlying structural dynamics. We explore how the photoelectron spectra distinctly reflect the different protonation states that are generated by variation of the solution acidity and how the distribution of these protonation states can differ between bulk and surface regions. At specific pH values, we find that the distribution of the cysteine species at the surface is quite different from that in bulk, in particular, for the appearance in the surface region of species which do not exist in bulk. Some ramifications of this finding are discussed
FUNDAÇÃO DE APOIO À PESQUISA DO DISTRITO FEDERAL - FAPDF
FINANCIADORA DE ESTUDOS E PROJETOS - FINEP
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ
COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES
FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP
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