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The Raman spectra of serine and 3,3-dideutero-serine in aqueous solution

Jarmelo, S.; Carey, P. R.; Fausto, R.
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
Relevância na Pesquisa
767.4545%
The Raman spectra of serine [[alpha]-amino-[beta]-hydroxypropionic acid; HOCH2CH(NH3)+COO-] and 3,3-dideutero-serine [HOCD2CH(NH3)+COO-] in aqueous solution were studied in the range 4000-300 cm-1. The data obtained for the deuterated compound are novel and provide compelling evidence that previously reported assignments for the undeuterated amino acid should be revised.; http://www.sciencedirect.com/science/article/B6THW-4KNMB16-1/1/19da7b30f32b5efeacb053228a66c4a4

Structure and vibrational properties of serine in a variety of chemical and biochemical environments

Dias, Susana Paula Jarmelo
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
505.08594%
As propriedades estruturais, energéticas e vibracionais da L- e DL-Ser e dos seus isotopólogos deuterados nas formas neutra e zwiteriónica, em diferentes ambientes químicos e bioquímicos, foram investigadas por espectroscopia de IR e Raman e métodos teóricos. A investigação da Superfície de Energia Potencial da serina na forma neutra foi realizada recorrendo aos métodos DFT e MP2. As estruturas e os espectros vibracionais dos confórmeros mais estáveis da serina foram calculados usando ambos os níveis de teoria e utilizados na interpretação dos resultados espectroscópicos obtidos para o composto isolado em matrizes de árgon a baixa temperatura. Os efeitos da entropia no equílibrio conformacional da serina foram também investigados. Além disso, foi efectuada irradiação in situ dos compostos isolados e realizados estudos de variação de temperatura da matriz. Os espectros de IV das amostras policristalinas puras da L- e DL-Ser e das espécies isotopicamente substítuidas foram investigados. Um método experimental assente na conjugação do uso de dopagem isotópica e de temperaturas baixas foi usado, conjuntamente com correlações empíricas, para estimar as energias e os comprimentos das diferentes ligações-de-hidrogénio presentes em ambos os cristais. Adicionalmente...

Preferred Conformers and Photochemical (λ > 200 nm) Reactivity of Serine and 3,3-Dideutero-Serine In the Neutral Form

Jarmelo, S.; Lapinski, L.; Nowak, M. J.; Carey, P. R.; Fausto, R.
Fonte: American Chemical Society Publicador: American Chemical Society
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
653.45535%
A systematic investigation of the conformational potential energy surface of neutral serine [HOCH2CHNH2COOH] and 3,3-dideutero-serine [HOCD2CHNH2COOH] was undertaken, revealing the existence of 61 different minima. The structures and vibrational spectra of the most stable conformers, which were estimated to have relative energies within 7 kJ mol-1 and account for ca. 93% of the total conformational population at room temperature, were calculated at both the MP2 and DFT/BLYP levels of theory with the 6-311++G(d,p) basis-set and used to interpret the spectroscopic data obtained for the compounds isolated in low-temperature inert matrixes. The assignment of the main spectral infrared features observed in the range 4000−400 cm-1 to the most stable conformers of serine was undertaken. In addition, UV irradiation (λ > 200 nm) of the matrix-isolated compounds was also performed, leading to decarboxylation, which was found to be strongly dependent on the conformation assumed by the reactant molecule.

Sulbactam Forms Only Minimal Amounts of Irreversible Acrylate-Enzyme With SHV-1 β-Lactamase

Totir, Monica A.; Helfand, Marion S.; Carey, Marianne P.; Sheri, Anjaneyulu; Buynak, John D.; Bonomo, Robert A.; Carey, Paul R.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
253.70086%
Sulbactam is a mechanism-based inhibitor of β-lactamase enzymes used in clinical practice. It undergoes a complex series of chemical reactions in the active site that have been studied extensively in the past three decades. However, the actual species that gives rise to inhibition in a clinical setting has not been established. Recent studies by our group, using Raman microscopy and X-ray crystallography, have found that large quantities of enamine-based acyl-enzyme species are present within minutes in single crystals of SHV-1 β-lactamases which can lead to significant inhibition. The enamines are formed by break down of the cyclic beta-lactam structures with further transformations leading to imine formation and subsequent isomerization to cis and/or trans enamines. Another favored form of inhibition arises from attack on the imine by a second nucleophilic amino acid side chain, e.g. from serine 130, to form a cross linked species in the active site that can degrade to an acrylate-like species irreversibly bound to the enzyme. Thus, the imine is at a branch point on the reaction pathway. Using sulbactam and 6,6-dideuterated sulbactam we follow these alternate paths in WT and E166A SHV-1 β-lactamase by means of Raman microscopic studies on single enzyme crystals. For the unlabeled sulbactam...