RESUMEN

BACKGROUND: Phospholipase D (PLD) is used as the biocatalyst for phosphatidylserine (PS) production. In general, PLD was expressed in insoluble form in Escherichia coli. High-level soluble expression of PLD with high activity in E. coli is very important for industrial production of PLD. RESULTS: Streptomyces chromofuscus PLD coding gene was codon-optimized, cloned without signal peptide, and expressed in E. coli. The optimal recombinant E. coli pET-28a+PLD/BL21(DE3) was constructed with pET-28a without His-tag. The highest PLD activity reached 104.28 ± 2.67 U/mL in a 250-mL shake flask after systematical optimization. The highest PLD activity elevated to 122.94 ± 1.49 U/mL by feeding lactose and inducing at 20 C after scaling up to a 5.0-L fermenter. Substituting the mixed carbon source with 1.0 % (w/v) of cheap dextrin and adding a feeding medium could still attain a PLD activity of 105. 81 ± 2.72 U/mL in a 5.0-L fermenter. Fish peptone from the waste of fish processing and dextrin from the starch are both very cheap, which were found to benefit the soluble PLD expression. CONCLUSIONS: After combinatorial optimization, the high-level soluble expression of PLD was fulfilled in E. coli. The high PLD activity along with cheap medium obtained at the fermenter level can completely meet the requirements of industrial production of PLD.

Asunto(s)

Fosfolipasas/metabolismo , Streptomyces/enzimología , Solubilidad , Streptomyces/genética , Temperatura , Codón , Técnicas Químicas Combinatorias , Escherichia coli

RESUMEN

Solid-phase synthesis represents the methodological showcase for technological advances such as split-and-pool combinatorial chemistry and the automated synthesis of peptides, nucleic acids and polysaccharides. These strategies involve iterative coupling cycles that do not generate functional diversity besides that incorporated by the amino acids, nucleosides and monosaccharide building blocks. In sharp contrast, multicomponent reactions (MCRs) are traditionally used to generate both skeletal and appendage diversity in short, batchwise procedures. On-resin MCRs have traditionally been employed for the construction of heterocycle and peptidomimetic libraries, but that scenario has changed recently, and today the focus is more on the solid-phase derivatization of peptides and oligonucleotides. This review presents relevant experimental details and addresses the synthetic scope of such on-resin multicomponent protocols employed to accomplish specific biopolymer covalent modifications that are practically inviable by traditional solution-phase methodologies. Recommendations are provided to facilitate the implementation of solid-supported protocols and avoid possible pitfalls associated with the selection of the polymeric resin, the solvent and the order and amount of the reagents employed. We describe procedures comprising the multicomponent lipidation, biotinylation and labeling of both termini and the side chains, as well as the use of MCRs in the traceless on-resin synthesis of ligated and cyclic peptides. Solid-phase protocols for the assembly of α-helical and parallel ß-sheet peptides as well as hybrid peptide-peptoid and peptide-peptide nucleic acid architectures are described. Finally, the solid-supported multicomponent derivatization of DNA oligonucleotides is illustrated as part of the DNA-encoded library technology relying on MCR-derived heterocyclic compounds.

Asunto(s)

Biopolímeros/química , Técnicas Químicas Combinatorias/métodos , Técnicas de Síntesis en Fase Sólida/métodos , Aminas , Aminoácidos , Biopolímeros/biosíntesis , Biotinilación , ADN , Compuestos Heterocíclicos , Oligonucleótidos , Péptidos/síntesis química , Péptidos Cíclicos , Resinas Sintéticas/química

RESUMEN

In this chapter, a protocol to design affinity chromatography matrices with short peptide ligands immobilized for protein purification is described. The first step consists of the synthesis of a combinatorial peptide library on the hydroxymethylbenzoyl (HMBA)-ChemMatrix resin by the divide-couple-recombine (DCR) method using the Fmoc chemistry. Next, the library is screened with the protein of interest labeled with a fluorescent dye or biotin. Subsequently, peptides contained on positive beads are identified by tandem matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS/MS), and those sequences showing greater consensus are synthesized in larger quantities and immobilized on chromatographic supports. Finally, target protein adsorption on peptide affinity matrices is evaluated through equilibrium adsorption isotherms and breakthrough curves.

Asunto(s)

Cromatografía de Afinidad , Técnicas Químicas Combinatorias , Biblioteca de Péptidos , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción

RESUMEN

Small molecule libraries for virtual screening are becoming a well-established tool for the identification of new hit compounds. As for experimental assays, the library quality, defined in terms of structural complexity and diversity, is crucial to increase the chance of a successful outcome in the screening campaign. In this context, Diversity-Oriented Synthesis has proven to be very effective, as the compounds generated are structurally complex and differ not only for the appendages, but also for the molecular scaffold. In this work, we automated the design of a library of lactams by applying a Diversity-Oriented Synthesis strategy called Build/Couple/Pair. We evaluated the novelty and diversity of these compounds by comparing them with lactam moieties contained in approved drugs, natural products, and bioactive compounds from ChEMBL. Finally, depending on their scaffold we classified them into ß-, γ-, δ-, ε-, and isolated, fused, bridged and spirolactam groups and we assessed their drug-like and lead-like properties, thus providing the value of this novel in silico designed library for medicinal chemistry applications.

Asunto(s)

Diseño de Fármacos , Lactamas/química , Bibliotecas de Moléculas Pequeñas/química , Productos Biológicos/química , Técnicas Químicas Combinatorias , Lactamas/metabolismo , Bibliotecas de Moléculas Pequeñas/metabolismo

RESUMEN

Peptide-based drug discovery is re-gaining attention in drug discovery. Similarly, combinatorial chemistry continues to be a useful technique for the rapid exploration of chemical space. A current challenge, however, is the enumeration of combinatorial peptide libraries using freely accessible tools. To facilitate the swift enumeration of combinatorial peptide libraries, we introduce herein D-Peptide Builder. In the current version, the user can build up to pentapeptides, linear or cyclic, using the natural pool of 20 amino acids. The user can use non- and/or N-methylated amino acids. The server also enables the rapid visualization of the chemical space of the newly enumerated peptides in comparison with other libraries relevant to drug discovery and preloaded in the server. D-Peptide Builder is freely accessible at http://dpeptidebuilder. quimica.unam.mx:4000/. It is also accessible through the open D-Tools platform (DIFACQUIM Tools for Chemoinformatics https://www.difacquim.com/d-tools/).

Asunto(s)

Técnicas Químicas Combinatorias , Internet , Biblioteca de Péptidos , Péptidos/química , Interfaz Usuario-Computador

RESUMEN

Focusing on the literature progress since 2002, the present review explores the highly significant role that multicomponent reactions (MCRs) have played as a very important tool for expedite synthesis of a vast number of organic molecules, but also, highlights the fact that many of such molecules are biologically active or at least have been submitted to any biological screen. The selected papers covered in this review must meet two mandatory requirements: (1) the reported products should be obtained via a multicomponent reaction; (2) the reported products should be biologically actives or at least tested for any biological property. Given the diversity of synthetic approaches utilized in MCRs, the highly diverse nature of the biological activities evaluated for the synthesized compounds, and considering their huge structural variability, much of the reported data are organized into concise schemes and tables to facilitate comparison, and to underscore the key points of this review.

Asunto(s)

Técnicas Químicas Combinatorias , Descubrimiento de Drogas , Catálisis , Humanos

RESUMEN

Copolymerization of isoprene (IP) with glycidyl methacrylate (GMA) was performed under RAFT (reversible addition-fragmentation chain-transfer) polymerization conditions in a platform for high-output experimentation. Covering the range between 1 and 0.2 molar fraction of IP in the feed, four sets of reactions were carried out at 10, 15, 20, and 30 h at 115 °C. The kinetic data obtained were used to estimate the reactivity ratios using a nonlinear least-squares approach (NLLS). Reactivity ratios rGMA = 0.61 and rIP = 0.74 indicate that both monomers tend to crosspropagate in agreement with known literature values. Concerning the RAFT study, relatively good control and livingness of the copolymerization was observed except for the experiment in which IP represents 20 mol % in the feed. 1H NMR characterization confirmed the presence of both monomers in the final copolymer, particularly the presence of the epoxy ring of GMA which is susceptible to post polymerization reactions. Finally, preliminary results on the hydrogenation of various polymers are discussed.

Asunto(s)

Butadienos/química , Compuestos Epoxi/química , Hemiterpenos/química , Metacrilatos/química , Polímeros/síntesis química , Técnicas Químicas Combinatorias , Estructura Molecular , Polimerizacion , Polímeros/química

RESUMEN

The present study reports a two-level multivariate analysis to optimize the production of anodized aluminum oxide (Al2O3) dielectric films for zinc oxide thin-film transistors (TFTs). Fourteen performance parameters were measured and analysis of variance (ANOVA) of the combined responses has been applied to identify how the Al2O3 dielectric fabrication process influences the electrical properties of the TFTs. Using this approach, the levels for the manufacturing factors to achieve optimal overall device performance have been identified and ranked. The cross-checked analysis of the TFT performance parameters demonstrated that the appropriate control of the anodization process can have a higher impact on TFT performance than the use of traditional methods of surface treatment of the dielectric layer. Flexible electronics applications are expected to grow substantially over the next 10 years. Given the complexity and challenges of new flexible electronics components, this "multivariate" approach could be adopted more widely by the industry to improve the reliability and performance of such devices.

Asunto(s)

Óxido de Aluminio/química , Transistores Electrónicos , Óxido de Zinc/química , Técnicas Químicas Combinatorias , Técnicas Electroquímicas , Electrodos , Análisis Multivariante

RESUMEN

Complexes of porphyrins and of other similar tetrapyrrolic macrocycles are extensively explored as catalysts for different chemical processes, and the development of solid catalysts for heterogeneous processes using molecules with the ability to act as multifunctional catalysts in one-pot reactions is increasing and can lead to the wider use of this class of molecules as catalysts. This mini review focuses on the application of this class of complexes as catalysts in a variety of sequential one-pot reactions.

Asunto(s)

Compuestos Macrocíclicos/química , Tetrapirroles/química , Catálisis , Técnicas de Química Sintética , Técnicas Químicas Combinatorias , Compuestos Macrocíclicos/síntesis química , Oxidación-Reducción , Relación Estructura-Actividad , Tetrapirroles/síntesis química

RESUMEN

A series of eight new 5-aryl-benzo[f][1,7]naphthyridines were synthesized in 17 to 64% overall yields via an improved MW-assisted cascade-like one pot process (Ugi⁻three component reaction/intramolecular aza-Diels-Alder cycloaddition) coupled to an aromatization process from tri-functional dienophile-containing ester-anilines, substituted benzaldehydes and the chain-ring tautomerizable 2-isocyano-1-morpholino-3-phenylpropan-1-one as starting reagents, under mild conditions. The doubly activated dienophile and the aza-diene functionalities of the eight new Ugi-adducts were exploited to perform an in situ aza-Diels-Alder cycloaddition/aromatization (dehydration/oxidation) process, toward the complex polysubstituted 5-aryl-polyheterocycles, which could be taken as starting point for further SAR studies because the benzo[f][1,7]naphthyridine is the core of various bioactive products. It is relevant to emphasize that the synthesis or isolation of benzo[f][1,7]naphthyridines containing a substituted aromatic ring in the C-5 position, has not been published before.

Asunto(s)

Ciclización , Reacción de Cicloadición , Naftiridinas/síntesis química , Técnicas Químicas Combinatorias , Microondas , Estructura Molecular , Naftiridinas/química

RESUMEN

Plants are extensively used in traditional medicine, and several plant antimicrobial peptides have been described as potential alternatives to conventional antibiotics. However, after more than four decades of research no plant antimicrobial peptide is currently used for treating bacterial infections, due to their length, post-translational modifications or  high dose requirement for a therapeutic effect . Here we report the design of antimicrobial peptides derived from a guava glycine-rich peptide using a genetic algorithm. This approach yields guavanin peptides, arginine-rich α-helical peptides that possess an unusual hydrophobic counterpart mainly composed of tyrosine residues. Guavanin 2 is characterized as a prototype peptide in terms of structure and activity. Nuclear magnetic resonance analysis indicates that the peptide adopts an α-helical structure in hydrophobic environments. Guavanin 2 is bactericidal at low concentrations, causing membrane disruption and triggering hyperpolarization. This computational approach for the exploration of natural products could be used to design effective peptide antibiotics.

Asunto(s)

Antibacterianos/química , Péptidos Catiónicos Antimicrobianos/química , Proteínas de Plantas/química , Infecciones por Pseudomonas/tratamiento farmacológico , Pseudomonas aeruginosa/efectos de los fármacos , Psidium/química , Algoritmos , Secuencia de Aminoácidos , Animales , Antibacterianos/biosíntesis , Antibacterianos/farmacología , Péptidos Catiónicos Antimicrobianos/biosíntesis , Péptidos Catiónicos Antimicrobianos/genética , Péptidos Catiónicos Antimicrobianos/farmacología , Membrana Celular/química , Membrana Celular/efectos de los fármacos , Técnicas Químicas Combinatorias , Diseño de Fármacos , Escherichia coli/efectos de los fármacos , Escherichia coli/crecimiento & desarrollo , Interacciones Hidrofóbicas e Hidrofílicas , Ratones , Modelos Moleculares , Resonancia Magnética Nuclear Biomolecular , Proteínas de Plantas/biosíntesis , Proteínas de Plantas/genética , Proteínas de Plantas/farmacología , Estructura Secundaria de Proteína , Infecciones por Pseudomonas/microbiología , Pseudomonas aeruginosa/química , Pseudomonas aeruginosa/crecimiento & desarrollo , Psidium/metabolismo , Piel/efectos de los fármacos , Piel/microbiología , Relación Estructura-Actividad

RESUMEN

The protein side-chain packing problem (PSCPP) is a central task in computational protein design. The problem is usually modeled as a combinatorial optimization problem, which consists of searching for a set of rotamers, from a given rotamer library, that minimizes a scoring function (SF). The SF is a weighted sum of terms, that can be decomposed in physics-based and knowledge-based terms. Although there are many methods to obtain approximate solutions for this problem, all of them have similar performances and there has not been a significant improvement in recent years. Studies on protein structure prediction and protein design revealed the limitations of current SFs to achieve further improvements for these two problems. In the same line, a recent work reported a similar result for the PSCPP. In this work, we ask whether or not this negative result regarding further improvements in performance is due to (i) an incorrect weighting of the SFs terms or (ii) the constrained conformation resulting from the protein crystallization process. To analyze these questions, we (i) model the PSCPP as a bi-objective combinatorial optimization problem, optimizing, at the same time, the two most important terms of two SFs of state-of-the-art algorithms and (ii) performed a preprocessing relaxation of the crystal structure through molecular dynamics to simulate the protein in the solvent and evaluated the performance of these two state-of-the-art SFs under these conditions. Our results indicate that (i) no matter what combination of weight factors we use the current SFs will not lead to better performances and (ii) the evaluated SFs will not be able to improve performance on relaxed structures. Furthermore, the experiments revealed that the SFs and the methods are biased toward crystallized structures.

Asunto(s)

Simulación de Dinámica Molecular , Proteínas/química , Algoritmos , Técnicas Químicas Combinatorias , Conformación Proteica

RESUMEN

Human schistosomiasis is a neglected tropical disease of great importance in public health. A large number of people are infected with schistosomiasis, making vaccine development and effective diagnosis important control strategies. A rational epitope prediction workflow using Schistosoma mansoni hypothetical proteins was previously presented by our group, and an improvement to that approach is presented here. Briefly, immunodominant epitopes from parasite membrane proteins were predicted by reverse vaccinology strategy with additional in silico analysis. Furthermore, epitope recognition was evaluated using sera of individuals infected with S. mansoni. The epitope that stood out in both in silico and in vitro assays was used to compose a rational chimeric molecule to improve immune response activation. Out of 2185 transmembrane proteins, four epitopes with high binding affinities for human and mouse MHCII molecules were selected through computational screening. These epitopes were synthesized to evaluate their ability to induce TCD4+ lymphocyte proliferation in mice. Sm204830e and Sm043300e induced significant TCD4+ proliferation. Both epitopes were submitted to enzyme-linked immunosorbent assay to evaluate their recognition by IgG antibodies from the sera of infected individuals, and epitope Sm043300 was significantly recognized in most sera samples. Epitope Sm043300 also showed good affinity for human MHCII molecules in molecular docking, and its sequence is curiously highly conserved in four S. mansoni proteins, all of which are described as G-protein-coupled receptors. In addition, we have demonstrated the feasibility of incorporating this epitope, which showed low similarity to human sequences, into a chimeric molecule. The stability of the molecule was evaluated by molecular modeling aimed at future molecule production for use in diagnosis and vaccination trials.

Asunto(s)

Antígenos Helmínticos/inmunología , Epítopos Inmunodominantes/inmunología , Schistosoma mansoni/inmunología , Secuencia de Aminoácidos , Animales , Anticuerpos Antihelmínticos/sangre , Anticuerpos Antihelmínticos/inmunología , Antígenos Helmínticos/genética , Linfocitos T CD4-Positivos/inmunología , Técnicas Químicas Combinatorias , Diseño de Fármacos , Evaluación Preclínica de Medicamentos , Femenino , Cadenas HLA-DRB1/inmunología , Proteínas del Helminto/química , Proteínas del Helminto/inmunología , Antígenos de Histocompatibilidad Clase II/inmunología , Antígenos de Histocompatibilidad Clase II/metabolismo , Humanos , Epítopos Inmunodominantes/genética , Epítopos Inmunodominantes/metabolismo , Activación de Linfocitos , Proteínas de la Membrana/química , Proteínas de la Membrana/inmunología , Ratones , Ratones Endogámicos C57BL , Modelos Moleculares , Simulación del Acoplamiento Molecular , Conformación Proteica , Receptores Acoplados a Proteínas G/química , Receptores Acoplados a Proteínas G/inmunología , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/inmunología , Schistosoma haematobium/inmunología , Schistosoma mansoni/genética , Esquistosomiasis mansoni/sangre , Esquistosomiasis mansoni/inmunología , Alineación de Secuencia , Vacunas de Subunidad/inmunología , Vacunas Sintéticas/inmunología

RESUMEN

Network-based strategies provided by systems biology are attractive tools for cancer therapy. Modulation of cancer networks by anticancer drugs may alter the response of malignant cells and/or drive network re-organization into the inhibition of cancer progression. Previously, using systems biology approach and cancer signaling networks, we identified top-5 highly expressed and connected proteins (HSP90AB1, CSNK2B, TK1, YWHAB and VIM) in the invasive MDA-MB-231 breast cancer cell line. Here, we have knocked down the expression of these proteins, individually or together using siRNAs. The transfected cell lines were assessed for in vitro cell growth, colony formation, migration and invasion relative to control transfected MDA-MB-231, the non-invasive MCF-7 breast carcinoma cell line and the non-tumoral mammary epithelial cell line MCF-10A. The knockdown of the top-5 upregulated connectivity hubs successfully inhibited the in vitro proliferation, colony formation, anchorage independence, migration and invasion in MDA-MB-231 cells; with minimal effects in the control transfected MDA-MB-231 cells or MCF-7 and MCF-10A cells. The in vitro validation of bioinformatics predictions regarding optimized multi-target selection for therapy suggests that protein expression levels together with protein-protein interaction network analysis may provide an optimized combinatorial target selection for a highly effective anti-metastatic precision therapy in triple-negative breast cancer. This approach increases the ability to identify not only druggable hubs as essential targets for cancer survival, but also interactions most susceptible to synergistic drug action. The data provided in this report constitute a preliminary step toward the personalized clinical application of our strategy to optimize the therapeutic use of anti-cancer drugs.

Asunto(s)

Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/patología , ARN Interferente Pequeño/metabolismo , Antineoplásicos/farmacología , Neoplasias de la Mama/metabolismo , Línea Celular Tumoral , Movimiento Celular , Proliferación Celular , Técnicas Químicas Combinatorias , Biología Computacional , Progresión de la Enfermedad , Femenino , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Humanos , Células MCF-7 , Invasividad Neoplásica , Transducción de Señal , Neoplasias de la Mama Triple Negativas/tratamiento farmacológico , Neoplasias de la Mama Triple Negativas/metabolismo , Neoplasias de la Mama Triple Negativas/patología

RESUMEN

A facile method for the preparation of cobalt ferrite nanotubes by use of bacterial cellulose nanoribbons as a template is described. The proposed method relays on a simple coprecipitation operation, which is a technique extensively used for the synthesis of nanoparticles (either isolated or as aggregates) but not for the synthesis of nanotubes. The precursors employed in the synthesis are chlorides, and the procedure is carried out at low temperature (90 °C). By the method proposed a homogeneous distribution of cobalt ferrite nanotubes with an average diameter of 217 nm in the bacterial nanocellulose (BC) aerogel (3%) was obtained. The obtained nanotubes are formed by 26-102 nm cobalt ferrite clusters of cobalt ferrite nanoparticles with diameters in the 9-13 nm interval. The nanoparticles that form the nanotubes showed to have a certain crystalline disorder, which could be attributed in a greater extent to the small crystallite size, and, in a lesser extent, to microstrains existing in the crystalline lattice. The BC-templated-CoFe2O4 nanotubes exhibited magnetic behavior at room temperature. The magnetic properties showed to be influenced by a fraction of nanoparticles in superparamagnetic state.

Asunto(s)

Celulosa/química , Cobalto/química , Compuestos Férricos/química , Nanopartículas/química , Bacterias/química , Técnicas Químicas Combinatorias/métodos , Microscopía Electrónica de Rastreo , Difracción de Rayos X

RESUMEN

INTRODUCTION: Aptamers are oligonucleotide molecules raised in vitro from large combinatorial libraries of nucleic acids and developed to bind to targets with high affinity and specificity. Whereas novel target molecules are proposed for therapeutic intervention and diagnostic, aptamer technology has a great potential to become a source of lead compounds. AREAS COVERED: In this review, the authors address the current status of the technology and highlight the recent progress in aptamer-based technologies. They also discuss the current major technical limitations of aptamer technology and propose original solutions based on existing technologies that could result in a solid aptamer-discovery platform. EXPERT OPINION: Whereas aptamers have shown to bind to targets with similar affinities and specificities to those of antibodies, aptamers have several advantages that could outweigh antibody technology and open new opportunities for better medical and diagnostic solutions. However, the current status of the aptamer technology suffers from several technical limitations that slowdown the progression of novel aptamers into the clinic and makes the business around aptamers challenging.

Asunto(s)

Aptámeros de Nucleótidos/administración & dosificación , Técnicas Químicas Combinatorias/métodos , Técnica SELEX de Producción de Aptámeros/métodos , Animales , Anticuerpos/administración & dosificación , Anticuerpos/metabolismo , Aptámeros de Nucleótidos/metabolismo , Biblioteca de Genes , Humanos

Asunto(s)

Técnicas Químicas Combinatorias , Descubrimiento de Drogas , Antineoplásicos/química , Descubrimiento de Drogas/tendencias

RESUMEN

The present study deals with the enzymatic synthesis of alkyl esters with emollient properties by a sequential hydrolysis/esterification process (hydroesterification) using unrefined macaw palm oil from pulp seeds (MPPO) as feedstock. Crude enzymatic extract from dormant castor bean seeds was used as biocatalyst in the production of free fatty acids (FFA) by hydrolysis of MPPO. Esterification of purified FFA with several alcohols in heptane medium was catalyzed by immobilized Thermomyces lanuginosus lipase (TLL) on poly-hydroxybutyrate (PHB) particles. Under optimal experimental conditions (mass ratio oil:buffer of 35% m/m, reaction temperature of 35 °C, biocatalyst concentration of 6% m/m, and stirring speed of 1,000 rpm), complete hydrolysis of MPPO was reached after 110 min of reaction. Maximum ester conversion percentage of 92.4 ± 0.4% was reached using hexanol as acyl acceptor at 750 mM of each reactant after 15 min of reaction. The biocatalyst retained full activity after eight successive cycles of esterification reaction. These results show that the proposed process is a promising strategy for the synthesis of alkyl esters of industrial interest from macaw palm oil, an attractive option for the Brazilian oleochemical industry.

Asunto(s)

Técnicas Químicas Combinatorias/métodos , Ésteres/síntesis química , Lipasa/química , Modelos Químicos , Aceites de Plantas/química , Semillas/química , Alquilación , Catálisis , Simulación por Computador , Enzimas Inmovilizadas/química , Esterificación , Proteínas Fúngicas/química , Hidrólisis , Aceite de Palma

RESUMEN

Short cyclic peptides have a great interest in therapeutic, diagnostic and affinity chromatography applications. The screening of 'one-bead-one-peptide' combinatorial libraries combined with mass spectrometry (MS) is an excellent tool to find peptides with affinity for any target protein. The fragmentation patterns of cyclic peptides are quite more complex than those of their linear counterparts, and the elucidation of the resulting tandem mass spectra is rather more difficult. Here, we propose a simple protocol for combinatorial cyclic libraries synthesis and ring opening before MS analysis. In this strategy, 4-hydroxymethylbenzoic acid, which forms a benzyl ester with the first amino acid, was used as the linker. A glycolamidic ester group was incorporated after the combinatorial positions by adding glycolic acid. The library synthesis protocol consisted in the following: (i) incorporation of Fmoc-Asp[2-phenylisopropyl (OPp)]-OH to Ala-Gly-oxymethylbenzamide-ChemMatrix, (ii) synthesis of the combinatorial library, (iii) assembly of a glycolic acid, (iv) couple of an Ala residue in the N-terminal, (v) removal of OPp, (vi) peptide cyclisation through side chain Asp and N-Ala amino terminus and (vii) removal of side chain protecting groups. In order to simultaneously open the ring and release each peptide, benzyl and glycolamidic esters were cleaved with ammonia. Peptide sequences could be deduced from the tandem mass spectra of each single bead evaluated. The strategy herein proposed is suitable for the preparation of one-bead-one-cyclic depsipeptide libraries that can be easily open for its sequencing by matrix-assisted laser desorption/ionisation MS. It employs techniques and reagents frequently used in a broad range of laboratories without special expertise in organic synthesis.

Asunto(s)

Depsipéptidos/química , Secuencia de Aminoácidos , Técnicas Químicas Combinatorias , Biblioteca de Péptidos , Análisis de Secuencia de Proteína , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción

RESUMEN

A practical one-pot synthesis of nicotine analogs from Ugi 4-CR/propargyl adducts is reported. This methodology allows the rapid construction of the pyrrolidine moiety present in nicotine through an intramolecular base-promoted 5-endo cycloisomerization process, followed by a reduction of the resulting mixture of 2- and 3-pyrrolines to afford nicotine analogs in good overall yields.

Asunto(s)

Técnicas Químicas Combinatorias/métodos , Nicotina/análogos & derivados , Nicotina/síntesis química , Catálisis , Ciclización , Éteres de Hidroxibenzoatos/química , Estructura Molecular , Nicotina/química , Oxidación-Reducción , Paladio/química , Pargilina/análogos & derivados , Pargilina/química , Propilaminas/química , Piridinas/química , Estereoisomerismo