Página 1 dos resultados de 4627 itens digitais encontrados em 0.035 segundos

Prediction of 99mtc-biguanide complex structures and their interactions with biological molecules by molecular mechanics calculations

Neves, M.; Fausto, R.
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
Português
Relevância na Pesquisa
55.81%
The structures of some Tc-biguanide complexes are predicted by molecular mechanics calculations. In addition, simulations of molecular interactions between the predicted equilibrium structures with water molecules or peptide chains are correlated with experimental data of partition coefficients and percentage of human protein binding, evaluated for the analogous 99mTc-biguanide complexes. These results suggest the value of computer-assisted design of new Tc-radiopharmaceuticals, and in particularly, stress the great interest of using molecular modelling to predict molecular properties that can be successfully correlated with results obtained by in vitro studies.; http://www.sciencedirect.com/science/article/B6T9Y-3VH7RJ1-F/1/28c6254dbf87e9167c6d54b03225652c

Molecular modeling of the interaction of novel hydroxy- and aminobisphosphonates with hydroxyapatite

Duarte, Luís F.; Teixeira, Fátima C.; Fausto, Rui
Fonte: ARKAT-USA, Inc. Publicador: ARKAT-USA, Inc.
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
55.89%
Bisphosphonates (BPs) are a class of drugs widely used in the treatment of several metabolic bone disorders associated with increased bone resorption. Although BPs can directly inhibit the cellular activity of osteoclasts, their ability to adsorb on bone mineral is also an important factor in determining their potency and duration of action. In this study, we performed a molecular mechanics analysis of the molecular structures of 18 novel hydroxy- and aminobisphosphonates and examined their interactions with hydroxyapatite. From the calculated interaction energies, general rules were extracted relating structural characteristics of BPs and their affinities to the mineral. The results obtained were shown to be in agreement with in vitro and in vivo studies performed for some of the studied BPs. Keywords: Bisphosphonates, hydroxyapatite binding, molecular modeling, molecular mechanics; This paper is dedicated to Prof. António M. d’A. Rocha Gonçalves. In his classes of organic chemistry, at the University of Coimbra, he was the first to show me the beauty of structural chemistry (R.F.)

Análise da estrutura molecular de compostos orgânicos por difração de raios-x e mecânica molecular.; Molecular structure analysis of organic compounds by X-ray diffraction and molecular mechanics.

Costa, Maria Cristina Nonato
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 19/03/1993 Português
Relevância na Pesquisa
66.03%
Este trabalho visou a análise estrutural de três compostos orgânicos: [A] : (2SR, 8SR)-2-(8-O-borinil-8-fenil)etil piperidina (C17H28NOB), [B] : (1SR, 2SR)-1-p-Bromoanilina-1-fenil-2-metil-3-pentanona -(C18H20NOBr) e [C] : um triterpeno-(C30O3H46) por difração de raio-X e por mecânica molecular. As estruturas no estado sólido foram primeiramente obtidas por difração de raios-x por monocristais, e posteriormente analisadas por mecânica molecular. [A]: monoclínico, grupo espacial C2/c, a=15.259(3)Å, b=12.574(2)Å, c=17.413(5)Å, β=94.44°, Z=8, Dx=1.089 g/cm3, V=3331.45޵ as estruturas cristalográficas e por mecânica molecular não apresentam grandes desvios. [B]: triclínico, grupo espacial P1¯, a=8.467(7)Å, b=8.7361(3)Å, c=12.468(9)Å, α=82.401(5)°, β=83.096(6)°, ϒ=69.026(5)°, Z=2, Dx=1.430 g/cm3, V=850.95޵ a principal diferença entre as duas estruturas cristalográfica e por mecânica molecular está no ângulo de torsão C(2)-C(1)-N-C(8) de 59.8°. Entre as moléculas relacionadas pelo centro de inversão existe duas pontes de hidrogênio entre os átomos O-N. [C]: ortorrômbico, grupo espacial P212121, a=7.314(7)Å, b=12.807(3)Å, c=26.812(5)Å...

Análise da via de regulação gênica por ácido retinóico: uma abordagem por bioinformática e biologia estrutural; Analysis of retinoic acid pathway: an approach by bioinformatics and structural biology.

Sobreira, Tiago José Paschoal
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 11/12/2008 Português
Relevância na Pesquisa
45.96%
As vias de sinalização celular por meio de moléculas são um dos principais meios de controle funcional de um organismo. O entendimento das funções de moléculas sinalizadoras facilita a compreensão das vias metabólicas de um organismo, assim possibilitando uma melhor compreensão de vários eventos biológicos e também de várias doenças. A sinalização pelo ácido retinóico (AR), e seus derivados, é responsável pelo controle de várias funções, por exemplo: crescimento celular, diferenciação celular, formação da retina, desenvolvimento cardíaco e também relacionado a várias patologias como diabetes, obesidades, cânceres, e doenças cardiovasculares. A ação do ácido retinóico é controlada em dois níveis: no metabolismo de síntese/degradação e na sua utilização na sinalização para a expressão gênica. A maquinaria que controla o metabolismo inclui as enzimas de síntese do AR (aldeído desidrogenase ALDH) e as enzimas de degradação do AR (Cyp26), que controlam a distribuição espaço-temporal do AR durante a embriogênese. As ALDHs são enzimas NAD(P)+ dependentes, que oxidam uma ampla gama de aldeídos para os seus correspondentes ácidos carboxílicos, sendo ALDH1A2 a principal enzima na transformação de retinal em ácido retinóico. A maquinaria da sinalização celular por AR contém os receptores nucleares controlados por AR (RARs) que estão envolvidos com o controle da transcrição gênica. Os mecanismos de controle de expressão mais comuns são os que ocorrem na fase transcricional. Um desses mecanismos envolve proteínas que se ligam às regiões promotoras de transcrição...

Aglomerados de pentaceno e nanotubos de carbono: um estudo MM/MQ (mecânica molecular/mecânica quântica); Pentacene and carbon nantubes clusters: A MM/MQ (molecular mechanics/quantum mechanics) study

Padilha, Antonio Claudio Michejevs
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 22/09/2011 Português
Relevância na Pesquisa
65.95%
Nanotubos de carbono e polímeros condutores são fortes candidatos à miniaturização dos componentes eletrônicos disponíveis atualmente. Estudos teóricos afirmaram que 1/3 dos nanotubos seriam metálicos, enquanto que os outros seriam semicondutores, mas alguns grupos reportaram medidas experimentais evidenciando um pequeno gap eletrônico em tubos considerados metálicos. Protótipos de transístores compostos de nanotubos e moléculas orgânicas conjugadas foram propostos e foi observado que o recobrimento dos tubos por moléculas de pentaceno tornava os dispositivos menos suscetíveis à deposição de impurezas, o que diminuía a histerese na curva característica i x V, ao mesmo tempo que a formação de cristais de pentaceno era favorecida. Neste trabalho estudamos a estrutura eletrônica dos nanotubos (5,5) e (9,0) través de DFT e observamos presença de um gap nesses sistemas, assim como uma deformação de suas estruturas de ligações químicas, evidenciando a distorção de Peierls. O efeito do termo de troca de Hartree-Fock introduzido no funcional B3LYP foi avaliado variando-se seu peso e observando as propriedades destes sistemas. Em uma segunda etapa, utilizamos mecânica molecular e dinâmica molecular clássica com o campo de forças CVFF 950 e observamos a formação de estruturas de pentaceno em volta dos tubos...

Modelação molecular de associações entre aniões e receptores sintéticos

Santos, Sérgio Miguel Fernandes dos
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
45.96%
A aplicação de simulações de mecânica e dinâmica molecular ao estudo de sistemas supramoleculares tem adquirido, ao longo dos últimos anos, enorme relevância. A sua utilização não só tem levado a uma melhor compreensão dos mecanismos de formação desses mesmos sistemas, como também tem fornecido um meio para o desenvolvimento de novas arquitecturas supramoleculares. Nesta tese são descritos os trabalhos de mecânica e dinâmica molecular desenvolvidos no âmbito do estudo de associações supramoleculares entre aniões e receptores sintéticos do tipo [2]catenano, [2]rotaxano e pseudorotaxano. São ainda estudados complexos supramoleculares envolvendo receptores heteroditópicos do tipo calix[4]diquinona e pares iónicos formados por aniões halogeneto e catiões alcalinos e amónio. Os estudos aqui apresentados assentam essencialmente em duas vertentes: no estudo das propriedades dinâmicas em solução dos vários complexos supramoleculares considerados e no cálculo das energias livres de Gibbs de associação relativas dos vários iões aos receptores sintéticos. As metodologias utilizadas passaram por dinâmica molecular convencional e REMD (Replica Exchange Molecular Dynamics), para o estudo das propriedades em solução...

Molecular modeling of the interaction of novel hydroxy-and aminobisphosphonates with hydroxyapatite

Duarte, L. F.; Teixeira, Fátima C.; Fausto, R.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Artigo de Revista Científica
Publicado em //2010 Português
Relevância na Pesquisa
55.8%
Bisphosphonates (BPs) are a class of drugs widely used in the treatment of several metabolic bone disorders associated with increased bone resorption. Although BPs can directly inhibit the cellular activity of osteoclasts, their ability to adsorb on bone mineral is also an important factor in determining their potency and duration of action. In this study, we performed a molecular mechanics analysis of the molecular structures of 18 novel hydroxy- and aminobisphosphonates and examined their interactions with hydroxyapatite. From the calculated interaction energies, general rules were extracted relating structural characteristics of BPs and their affinities to the mineral. The results obtained were shown to be in agreement with in vitro and in vivo studies performed for some of the studied BPs.

Molecular mechanics application in inorganic Chemistry

Coelho,Lilian Weitzel; Junqueira,Georgia Maria Amaral; Machuca Herrera,Juan Omar; Machado,Sérgio de Paula; Machado,Bianca da Cunha
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/1999 Português
Relevância na Pesquisa
65.91%
The present paper is a review about basic principles of the molecular mechanics that is the most important tool used in molecular modeling area, and their applications to the calculation of the relative stability and chemical reactivity of organometalic and coordination compounds. We show how molecular mechanics can be successfully applied to a wide variety of inorganic systems.

Metodologia para obtenção de parâmetros de mecânica molecular aplicados a compostos de coordenação

Almeida,Carlos Henrique Ferreira; Machuca-Herrera,Juan Omar; Machado,Sérgio de Paula
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/2002 Português
Relevância na Pesquisa
55.85%
A methodology is presented to obtain force field parameters to be used in molecular mechanics. The case of Ru(II) is investigated and the parameters obtained, specially its covalent radii, are employed to model Ru(II) coordination compound. The combined use of molecular mechanics with ab initio methods allowed us to predict the metal-ligand stretching force constant for Ru(II) coordination compounds.

MKTOP: a program for automatic construction of molecular topologies

Ribeiro,André A. S. T.; Horta,Bruno A. C.; Alencastro,Ricardo B. de
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2008 Português
Relevância na Pesquisa
55.81%
Molecular mechanics methods are widely-used for simulations of biomolecules. A molecular topology file containing all atom types, which depend on the chemical environment, must be constructed. MKTOP is a free-software capable of automatic atom type recognition and construction of molecular topologies for GROMACS, being a useful tool for its users.

Design of Protein-Ligand Binding Based on the Molecular-Mechanics Energy Model

Boas, F. Edward; Harbury, Pehr B.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
45.99%
While the molecular-mechanics field has standardized on a few potential energy functions, computational protein design efforts are based on potentials that are unique to individual labs. Here we show that a standard molecular-mechanics potential energy function without any modifications can be used to engineer protein-ligand binding. A molecular-mechanics potential is used to reconstruct the coordinates of various binding sites with an average root mean square error of 0.61 Å, and to reproduce known ligand-induced side-chain conformational shifts. Within a series of 34 mutants, the calculation can always distinguish weak (Kd > 1 mM) and tight (Kd < 10 µM) binding sequences. Starting from partial coordinates of the ribose binding protein lacking the ligand and the ten primary contact residues, the molecular-mechanics potential is used to redesign a ribose binding site. Out of a search space of 2×1012 sequences, the calculation selects a point mutant of the native protein as the top solution (experimental Kd = 17 µM), and the native protein as the second best solution (experimental Kd = 210 nM). The quality of the predictions depends on the accuracy of the generalized Born electrostatics model, treatment of protonation equilibria...

Analysis of the Conformational Stability and Activity of Candida antarctica Lipase B in Organic Solvents: INSIGHT FROM MOLECULAR DYNAMICS AND QUANTUM MECHANICS/SIMULATIONS*

Li, Cong; Tan, Tianwei; Zhang, Haiyang; Feng, Wei
Fonte: American Society for Biochemistry and Molecular Biology Publicador: American Society for Biochemistry and Molecular Biology
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
45.94%
The conformational stability and activity of Candida antarctica lipase B (CALB) in the polar and nonpolar organic solvents were investigated by molecular dynamics and quantum mechanics/molecular mechanics simulations. The conformation change of CALB in the polar and nonpolar solvents was examined in two aspects: the overall conformation change of CALB and the conformation change of the active site. The simulation results show that the overall conformation of CALB is stable in the organic solvents. In the nonpolar solvents, the conformation of the active site keeps stable, whereas in the polar solvents, the solvent molecules reach into the active site and interact intensively with the active site. This interaction destroys the hydrogen bonding between Ser105 and His224. In the solvents, the activation energy of CALB and that of the active site region were further simulated by quantum mechanics/molecular mechanics simulation. The results indicate that the conformation change in the region of active sites is the main factor that influences the activity of CALB.

A Molecular Dynamics (MD) and Quantum Mechanics/Molecular Mechanics (QM/MM) Study on Ornithine Cyclodeaminase (OCD): A Tale of Two Iminiums

Ion, Bogdan F.; Bushnell, Eric A. C.; De Luna, Phil; Gauld, James W.
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 11/10/2012 Português
Relevância na Pesquisa
55.91%
Ornithine cyclodeaminase (OCD) is an NAD+-dependent deaminase that is found in bacterial species such as Pseudomonas putida. Importantly, it catalyzes the direct conversion of the amino acid L-ornithine to L-proline. Using molecular dynamics (MD) and a hybrid quantum mechanics/molecular mechanics (QM/MM) method in the ONIOM formalism, the catalytic mechanism of OCD has been examined. The rate limiting step is calculated to be the initial step in the overall mechanism: hydride transfer from the L-ornithine’s Cα–H group to the NAD+ cofactor with concomitant formation of a Cα=NH2 + Schiff base with a barrier of 90.6 kJ mol−1. Importantly, no water is observed within the active site during the MD simulations suitably positioned to hydrolyze the Cα=NH2 + intermediate to form the corresponding carbonyl. Instead, the reaction proceeds via a non-hydrolytic mechanism involving direct nucleophilic attack of the δ-amine at the Cα-position. This is then followed by cleavage and loss of the α-NH2 group to give the Δ1-pyrroline-2-carboxylate that is subsequently reduced to L-proline.

Molecular Mechanics Study of Nickel(II) Octaethylporphyrin Adsorbed on Graphite(0001)

Gruden-Pavlović, Maja; Grubišić, Sonja; Zlatar, Matija; Niketić, Svetozar R.
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 21/08/2007 Português
Relevância na Pesquisa
55.76%
The effects of adsorption on the graphite(0001) surface on the nonplanar distortions of nickel(II)octaethylporphyrin were studied by molecular mechanics (MM) approach. Using the Consistent Force Field (CFF) program with previously developed parameters for metalloporphyrins and supplemented to treat intermolecular interactions geometry optimizations were carried out for 43 conformations of 28 distinct conformers of nickel(II)octaethylporphyrin. The stable energy-minimized conformers were stereochemically characterized, analyzed by the Normal-coordinate Structural Decomposition (NSD) method and compared with the available theoretical and experimental data for the isolated nickel(II)octaethylporphyrin structures.

Molecular mechanics calculations on some phosphine oxide metal complexes in aqueous and organic solvents

Mwakapumba, Joseph.
Fonte: Brock University Publicador: Brock University
Tipo: Electronic Thesis or Dissertation
Português
Relevância na Pesquisa
55.79%
Molecular mechanics calculations were done on tetrahedral phosphine oxide zinc complexes in simulated water, benzene and hexane phases using the DREIDING II force field in the BIOGRAF molecular modeling program. The SUN workstation computer (SUN_ 4c, with SPARK station 1 processor) was used for the calculations. Experimental structural information used in the parameterization was obtained from the September 1989 version of the Cambridge Structural Database. 2 Steric and solvation energies were calculated for complexes of the type ZnCl2 (RlO)2' The calculations were done with and without inclusion of electrostatic interactions. More reliable simulation results were obtained without inclusion of charges. In the simulated gas phase, the steric energies increase regularly with number of carbons in the alkyl group, whereas they go through a maximum when solvent shells are included in the calculation. Simulated distribution ratios vary with chain length and type of chain branching and the complexes are found to be more favourable for extraction by benzene than by hexane, in accord with experimental data. Also, in line with what would be expected for a favorable extraction, calculations without electrostatics predict that the complexes are better solvated by the organic solvents than by water.

The importance of reactant positioning in enzyme catalysis: A hybrid quantum mechanics/molecular mechanics study of a haloalkane dehalogenase

Lau, Edmond Y.; Kahn, Kalju; Bash, Paul A.; Bruice, Thomas C.
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Publicado em 29/08/2000 Português
Relevância na Pesquisa
45.96%
Hybrid quantum mechanics/molecular mechanics calculations using Austin Model 1 system-specific parameters were performed to study the SN2 displacement reaction of chloride from 1,2-dichloroethane (DCE) by nucleophilic attack of the carboxylate of acetate in the gas phase and by Asp-124 in the active site of haloalkane dehalogenase from Xanthobacter autotrophicus GJ10. The activation barrier for nucleophilic attack of acetate on DCE depends greatly on the reactants having a geometry resembling that in the enzyme or an optimized gas-phase structure. It was found in the gas-phase calculations that the activation barrier is 9 kcal/mol lower when dihedral constraints are used to restrict the carboxylate nucleophile geometry to that in the enzyme relative to the geometries for the reactants without dihedral constraints. The calculated quantum mechanics/molecular mechanics activation barriers for the enzymatic reaction are 16.2 and 19.4 kcal/mol when the geometry of the reactants is in a near attack conformer from molecular dynamics and in a conformer similar to the crystal structure (DCE is gauche), respectively. This haloalkane dehalogenase lowers the activation barrier for dehalogenation of DCE by 2–4 kcal/mol relative to the single point energies of the enzyme's quantum mechanics atoms in the gas phase. SN2 displacements of this sort in water are infinitely slower than in the gas phase. The modest lowering of the activation barrier by the enzyme relative to the reaction in the gas phase is consistent with mutation experiments.

Molecular mechanics applied to single-walled carbon nanotubes

Ávila,Antonio Ferreira; Lacerda,Guilherme Silveira Rachid
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2008 Português
Relevância na Pesquisa
65.97%
Single-walled carbon nanotubes, with stiffness of 1.0 TPa and strength of 60 GPa, are a natural choice for high strength materials. A problem, however, arises when experimental data are compiled. The large variability of experimental data leads to the development of numerical models denominated molecular mechanics, which is a "symbiotic" association of molecular dynamics and solid mechanics. This paper deals with molecular mechanics simulations of single-walled carbon nanotubes. To be able to evaluate the molecular mechanics model, the three major carbon nanotube configurations (armchair, zigzag and chiral) were simulated. It was proven that the carbon nanotube configuration has influence on stiffness. By varying the radius, hence the curvature, the Young's modulus changed from 0.95 TPa to 5.5 TPa, and the Poisson's ratio ranged from 0.15 to 0.29. The numerical simulations were in good agreement with those presented in the literature.

Solvent effects on the asymmetric Diels-Alder reaction between cyclopentadiene and (-)-menthyl acrylate revisited with the three-layer hybrid local self-consistent field/molecular mechanics/self-consistent reaction field method

Loos, Pierre-Francois; Yohann, Moreau; Assfeld, Xavier
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
65.89%
The construction of the three-layer hybrid local self-consistent field/molecular mechanics/self-consistent reaction field method is detailed. This method is specifically devoted to the study of the reactivity of large chemical systems in solution. The sol

Study of molecular mechanisms in glycoside hydrolases and transferases by ab initio molecular dinyamics

Ardèvol Grau, Albert
Fonte: [Barcelona] : Universitat Autònoma de Barcelona. Departament de Bioquímica i Biologia Molecular, Publicador: [Barcelona] : Universitat Autònoma de Barcelona. Departament de Bioquímica i Biologia Molecular,
Tipo: Tesis i dissertacions electròniques; info:eu-repo/semantics/doctoralThesis Formato: application/pdf
Publicado em //2012 Português
Relevância na Pesquisa
65.84%
Descripció del recurs: el 01 setembre 2012; Carbohydrates had historically been associated to two biological functions: energy storage and structural support. However, in the last decades, new complex structures of oligosaccharides have been found to play vital roles in many biological processes, such as signal transduction, immune response, cell differentiation and cancer development, among others. Advances in the functional understanding of carbohydrate-protein interactions represented a breakthrough in the field of glycobiology and glycochemistry, opening a new branch of potential therapeutic targets (carbohydrate acting enzymes), glycomimetic drugs and biomarkers. The bottleneck in the field of glycochemistry is the synthesis of complex saccharides; hence many efforts have been devoted to the development of novel enzymatic strategies for carbohydrate synthesis. Glycoside transferases (GT) and glycoside hydrolases (GH) are the enzymes that catalyze the formation and the cleavage of the glycosidic linkage respectively. They are used in complex oligosaccharides synthesis, and recently they have been engineered to produce enzymes with particular substrate specificities or even activities. In spite of these advances, the understanding of the molecular mechanisms of enzymatic carbohydrate synthesis and degradation is far from complete. Structural studies have shown that the puckering of the sugar ring at the cleavage point must change during catalysis. Knowing the conformational catalytic itinerary has an impact in the design of GHs inhibitors. However...

Development and applications of molecular modelling techniques for the design and optimization of artificial metalloenzymes

Muñoz Robles, Victor
Fonte: [Barcelona] : Universitat Autònoma de Barcelona, Publicador: [Barcelona] : Universitat Autònoma de Barcelona,
Tipo: Tesis i dissertacions electròniques; info:eu-repo/semantics/doctoralThesis; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2014 Português
Relevância na Pesquisa
45.92%
La búsqueda de procesos de síntesis de moléculas orgánicas altamente eficientes y selectivos es uno de los retos de la química. En los últimos años, las enzimas se han presentado como una seria alternativa a los catalizadores homogéneos tradicionales debido a su alta eficiencia y selectividad natural. Desafortunadamente, las reacciones que pueden catalizar estas especies se suelen restringir a aquellas que tienen importancia para el huésped que las alberga, limitando su aplicación en el ámbito químico/industrial. Para poder solventar estas limitaciones se han desarrollado las llamadas metaloenzimas artificiales. Estos híbridos se obtienen a partir de la inserción de un catalizador homogéneo en una proteína. De este modo el receptor protege el cofactor inorgánico y aporta un entorno quiral (enantioselectivo) mientras que el metal es responsable de la reactividad del sistema. Pero el diseño de estos híbridos representa todo un reto: la proteína no ha sido diseñada evolutivamente para reconocer el fragmento inorgánico y el complejo resultante puede no reconocer de forma eficiente el sustrato. Todo esto provoca que la enzima diseñada presente deficiencias en cuanto a la eficiencia catalítica y/o selectividad. Las técnicas de modelización molecular pueden resultar de gran ayuda en el proceso de diseño y de optimización de las metaloenzimas artificiales. Sin embargo...