RESUMO
A chiral derivatizing agent (CDA) with the aldehyde function has been widely used in discriminating chiral amines because of the easy formation of imines under mild conditions. There is a preference for the use of cyclic aldehydes as a CDA since their lower conformational flexibility favors the differentiation of the diastereoisomeric derivatives. In this study, the imines obtained from the reaction between (S)-citronellal and the chiral amines (sec-butylamine, methylbenzylamine, and amphetamine) were analyzed by the nuclear Overhauser effect (NOE). Through NOE, it was possible to observe that the ends of the molecules were close, suggesting a quasi-folded conformation. This conformation was confirmed by theoretical calculations that indicated the London forces and the molecular orbitals as main justifications for this conformation. This conformational locking explains the good separation of 13C NMR signals between the diastereomeric imines obtained and, consequently, a good determination of the enantiomeric excess using the open chain (S)-citronellal as a CDA.
Assuntos
Monoterpenos Acíclicos/química , Aldeídos/química , Anfetamina/química , Benzilaminas/química , Butilaminas/química , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13 , Espectroscopia de Prótons por Ressonância Magnética , Monoterpenos Acíclicos/farmacologia , Aldeídos/farmacologia , Algoritmos , Modelos Moleculares , Modelos Teóricos , Estrutura MolecularRESUMO
Acumuladores são pessoas reconhecidas por reunir excessivamente objetos ou animais domésticos de forma desordenada e desorganizada. Geralmente vivem em locais com déficit de higiene, de autocuidado do corpo e do ambiente habitacional interferindo na sua qualidade de vida, de sua família e da comunidade onde vive. Na comunidade há potencial de risco para ocorrência de algumas endemias transmitidas por vetores, hospedeiros, incômodos e peçonhentos. O objetivo do estudo foi realizar uma revisão de evidências na literatura sobre acumuladores de materiais / objetos (síndrome de Diógenes) e de animais domésticos (síndrome de Noé) e seu impacto para a saúde com foco nas endemias. Uma pergunta estruturada orientou o método, com levantamento de termos em três idiomas, nas bases de dados de PubMed, Embase, Cochrane, Web of Science, Portal Regional da BVS, Google Acadêmico, além de literatura cinzenta.
Assuntos
Humanos , Doença , Doenças Endêmicas , Transtorno de AcumulaçãoRESUMO
Sulfated fucans, sulfated galactans, and glycosaminoglycans are extensively studied worldwide in terms of both structure and biomedical functions. Liquid-state nuclear magnetic resonance (NMR) spectroscopy is the most employed analytical technique in structural analysis of these sulfated glycans. This is due to the fact that NMR-based analyses enable a series of achievements such as (i) accurate structure characterization/determination; (ii) measurements of parameters regarding molecular motion (dynamics); (iii) assessment of the 3D structures (usually assisted by computational techniques of Molecular Modeling and/or Molecular Dynamics) of the composing monosaccharides (ring conformers) and the overall conformational states of the glycan chains either free in solution or bound to proteins; and (iv) analysis of the resultant intermolecular complexes with functional proteins through either the protein or the carbohydrate perspective. In this review, after a general introduction about the principal NMR parameters utilized for achieving this set of structural information, discussion is given on NMR-based studies of some representative sulfated fucans, sulfated galactans, and glycosaminoglycans. Due to the growing number of studies concerning both structure and function of sulfated glycans and the widely use of NMR spectroscopy in such studies, a review paper discussing (i) the most experiments employed for analysis, (ii) procedures used in data interpretation, and (iii) the general aspects of the sulfated glycans, is timely in the literature.
Assuntos
Espectroscopia de Ressonância Magnética , Conformação Molecular , Polissacarídeos/química , Carboidratos/química , Substâncias Macromoleculares/química , Substâncias Macromoleculares/metabolismo , Espectroscopia de Ressonância Magnética/métodos , Modelos Químicos , Modelos Moleculares , Simulação de Dinâmica Molecular , Polissacarídeos/metabolismo , Ligação Proteica , Proteínas/química , Proteínas/metabolismo , Relação Estrutura-AtividadeRESUMO
When there were giants on the earth, two of them, Rudolf Kraus and Giovanni Noe, met at the ancient Bacteriological Institute of Chile, and founded together a journal representing the principles of the institution. A nostalgic glance over the papers published therein for these so named giants lets us know a little about the study of infectious diseases in the thirties, when tuberculosis and malaria were two of the biggest problems for the world’s public health... then and now.
Cuando había gigantes sobre la Tierra, dos de ellos, Rodolfo Kraus y Juan Noé, austriaco el uno e italiano el otro, coincidieron por un tiempo en el antiguo Instituto Bacteriológico de Chile. Tuvieron entonces la idea de crear una revista que representara los fines de la institución y el progreso de la microbiología. Una mirada nostálgica sobre los artículos publicados en dicha revista, nos permite saber un poco sobre el estudio de las enfermedades infecciosas en los años treinta, cuando la tuberculosis y la malaria eran dos de los mayores problemas para salud pública en el mundo... entonces y ahora.
Assuntos
História do Século XX , Publicações Periódicas como Assunto/história , Sociedades Médicas/história , Austrália , Infecções por Bartonella/história , Chile , Itália , Malária/história , Tuberculose/históriaRESUMO
Sulfated fucans from sea urchin egg jelly express well-defined chemical structures that vary with species. This species specificity regulates the sperm acrosome reaction, a critical step to assure intra-specific fertilization. In addition, these polysaccharides are involved in other biological activities such as anticoagulation. Although sulfation patterns are relevant to the levels of response in both activities, conformation and dynamics of these glycans are also contributing factors. However, data about these features of sulfated fucans are very rare. To address this, we have employed nuclear magnetic resonance experiments combined with molecular dynamics on structurally defined oligosaccharides derived from two sulfated fucans. The results have indicated that the oligosaccharides are flexible in solution. Ring conformation of their composing units displays just the (1)C4 chair configuration. In a particular octasaccharide, composed of two tetrasaccharide sequences, inter-residual hydrogen bonds play a role to decrease dynamics in these repeating units. Conversely, the linking disaccharide [-3)-α-L-Fucp-2(OSO3(-))-(1-3)-α-L-Fucp-4(OCO3(-))-(1-] located right between the two tetrasaccharide units has amplified motions suggested to be promoted by electrostatic repulsion of sulfates on opposite sides of the central glycosidic bond. This conjunction of information about conformation and dynamics of sulfated fucan oligosaccharides provides new insights to explain how these glycans behave free in solution and influenced by sulfation patterns. It may also serve for future studies concerning structure-function relationship of sulfated fucans, especially those involving sea urchin fertilization and anticoagulation.
Assuntos
Polissacarídeos/química , Animais , Configuração de Carboidratos , Simulação de Dinâmica Molecular , Ouriços-do-MarRESUMO
Human ß-defensins (hBDs) are believed to function as alarm molecules that stimulate the adaptive immune system when a threat is present. In addition to its antimicrobial activity, defensins present other activities such as chemoattraction of a range of different cell types to the sites of inflammation. We have solved the structure of the hBD6 by NMR spectroscopy that contains a conserved ß-defensin domain followed by an extended C-terminus. We use NMR to monitor the interaction of hBD6 with microvesicles shed by breast cancer cell lines and with peptides derived from the extracellular domain of CC chemokine receptor 2 (Nt-CCR2) possessing or not possessing sulfation on Tyr26 and Tyr28. The NMR-derived model of the hBD6/CCR2 complex reveals a contiguous binding surface on hBD6, which comprises amino acid residues of the α-helix and ß2-ß3 loop. The microvesicle binding surface partially overlaps with the chemokine receptor interface. NMR spin relaxation suggests that free hBD6 and the hBD6/CCR2 complex exhibit microsecond-to-millisecond conformational dynamics encompassing the CCR2 binding site, which might facilitate selection of the molecular configuration optimal for binding. These data offer new insights into the structure-function relation of the hBD6-CCR2 interaction, which is a promising target for the design of novel anticancer agents.