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1.
Life Sci ; 248: 117477, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32119961

RESUMO

AIMS: A newly emerged Human Coronavirus (HCoV) is reported two months ago in Wuhan, China (COVID-19). Until today >2700 deaths from the 80,000 confirmed cases reported mainly in China and 40 other countries. Human to human transmission is confirmed for COVID-19 by China a month ago. Based on the World Health Organization (WHO) reports, SARS HCoV is responsible for >8000 cases with confirmed 774 deaths. Additionally, MERS HCoV is responsible for 858 deaths out of about 2500 reported cases. The current study aims to test anti-HCV drugs against COVID-19 RNA dependent RNA polymerase (RdRp). MATERIALS AND METHODS: In this study, sequence analysis, modeling, and docking are used to build a model for Wuhan COVID-19 RdRp. Additionally, the newly emerged Wuhan HCoV RdRp model is targeted by anti-polymerase drugs, including the approved drugs Sofosbuvir and Ribavirin. KEY FINDINGS: The results suggest the effectiveness of Sofosbuvir, IDX-184, Ribavirin, and Remidisvir as potent drugs against the newly emerged HCoV disease. SIGNIFICANCE: The present study presents a perfect model for COVID-19 RdRp enabling its testing in silico against anti-polymerase drugs. Besides, the study presents some drugs that previously proved its efficiency against the newly emerged viral infection.


Assuntos
Monofosfato de Adenosina/análogos & derivados , Alanina/análogos & derivados , Antivirais/química , Betacoronavirus/enzimologia , Infecções por Coronavirus/tratamento farmacológico , Guanosina Monofosfato/análogos & derivados , Pneumonia Viral/tratamento farmacológico , RNA Replicase/antagonistas & inibidores , Ribavirina/química , Sofosbuvir/química , Proteínas Virais/antagonistas & inibidores , Monofosfato de Adenosina/química , Monofosfato de Adenosina/metabolismo , Alanina/química , Alanina/metabolismo , Alphacoronavirus/enzimologia , Alphacoronavirus/genética , Sequência de Aminoácidos , Antivirais/metabolismo , Betacoronavirus/genética , Domínio Catalítico , Biologia Computacional/métodos , Infecções por Coronavirus/virologia , Reposicionamento de Medicamentos/métodos , Guanosina Monofosfato/química , Guanosina Monofosfato/metabolismo , Guanosina Trifosfato/química , Guanosina Trifosfato/metabolismo , Humanos , Simulação de Acoplamento Molecular , Pneumonia Viral/virologia , Ligação Proteica , Conformação Proteica em alfa-Hélice , Conformação Proteica em Folha beta , Domínios e Motivos de Interação entre Proteínas , RNA Replicase/química , RNA Replicase/metabolismo , Ribavirina/metabolismo , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Sofosbuvir/metabolismo , Termodinâmica , Uridina Trifosfato/química , Uridina Trifosfato/metabolismo , Proteínas Virais/química , Proteínas Virais/metabolismo
2.
J Biol Chem ; 295(15): 4773-4779, 2020 04 10.
Artigo em Inglês | MEDLINE | ID: mdl-32094225

RESUMO

Antiviral drugs for managing infections with human coronaviruses are not yet approved, posing a serious challenge to current global efforts aimed at containing the outbreak of severe acute respiratory syndrome-coronavirus 2 (CoV-2). Remdesivir (RDV) is an investigational compound with a broad spectrum of antiviral activities against RNA viruses, including severe acute respiratory syndrome-CoV and Middle East respiratory syndrome (MERS-CoV). RDV is a nucleotide analog inhibitor of RNA-dependent RNA polymerases (RdRps). Here, we co-expressed the MERS-CoV nonstructural proteins nsp5, nsp7, nsp8, and nsp12 (RdRp) in insect cells as a part a polyprotein to study the mechanism of inhibition of MERS-CoV RdRp by RDV. We initially demonstrated that nsp8 and nsp12 form an active complex. The triphosphate form of the inhibitor (RDV-TP) competes with its natural counterpart ATP. Of note, the selectivity value for RDV-TP obtained here with a steady-state approach suggests that it is more efficiently incorporated than ATP and two other nucleotide analogs. Once incorporated at position i, the inhibitor caused RNA synthesis arrest at position i + 3. Hence, the likely mechanism of action is delayed RNA chain termination. The additional three nucleotides may protect the inhibitor from excision by the viral 3'-5' exonuclease activity. Together, these results help to explain the high potency of RDV against RNA viruses in cell-based assays.


Assuntos
Monofosfato de Adenosina/análogos & derivados , Alanina/análogos & derivados , Antivirais/farmacologia , Coronavírus da Síndrome Respiratória do Oriente Médio/enzimologia , Inibidores da Síntese de Ácido Nucleico/farmacologia , RNA Replicase/antagonistas & inibidores , Replicação Viral/efeitos dos fármacos , Monofosfato de Adenosina/química , Monofosfato de Adenosina/farmacologia , Alanina/química , Alanina/farmacologia , Animais , Antivirais/química , Coronavirus/enzimologia , Ebolavirus/enzimologia , Expressão Gênica , Inibidores da Síntese de Ácido Nucleico/química , RNA , RNA Replicase/genética , Células Sf9 , Proteínas não Estruturais Virais/genética
3.
Chemistry ; 26(14): 3049-3053, 2020 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-31961029

RESUMO

A general and powerful method for the stereo-controlled Pd-catalyzed N-allylation of amino acid esters is reported, as a previously largely unsolved synthetic challenge. Employing a new class of tartaric acid-derived C2 -symmetric chiral diphosphane ligands the developed asymmetric amination protocol allows the conversion of various amino acid esters to the N-allylated products with highest levels of enantio- or diastereoselectivity in a fully catalyst-controlled fashion and predictable configuration. Remarkably, the in situ generated catalysts also exhibit outstanding levels of activity (ligand acceleration). The usefulness of the method was demonstrated in the stereo-divergent synthesis of a set of new conformationally defined dipeptide mimetics, which represent new modular building blocks for the development of peptide-inspired bioactive compounds.


Assuntos
Aminoácidos/química , Dipeptídeos/síntese química , Ésteres/química , Paládio/química , Alanina/química , Catálise , Cristalografia por Raios X , Reação de Cicloadição , Ligantes , Modelos Moleculares , Estrutura Molecular , Oxirredução , Prolina/química , Estereoisomerismo
4.
J Environ Sci (China) ; 87: 250-259, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31791498

RESUMO

Water-uptakes of pure sodium carbonate (Na2CO3), pure ß-alanine and internally mixed ß-alanine/Na2CO3 aerosol particles with different mole ratios are first monitored using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) technique. For pure Na2CO3 aerosol particles, combining the absorptions at 877 and 1422 cm-1 with abrupt water loss shows the efflorescence relative humidity (ERH) of 62.9%-51.9%. Upon humidifying, solid Na2CO3 firstly absorbs water to from Na2CO3·H2O crystal at 72.0% RH and then deliquesces at 84.5% RH (DRH). As for pure ß-alanine particles, the crystallization takes place in the range of 42.4%-33.2% RH and becomes droplets at ~88.2% RH. When ß-alanine is mixed with Na2CO3 at various mole ratios, it shows no efflorescence of Na2CO3 when ß-alanine to Na2CO3 mole ratio (OIR) is 2:1. For 1:1 and 1:2 ß-alanine/Na2CO3 aerosols, the ERHs of Na2CO3 are 51.8%-42.3% and 57.1%-42.3%, respectively. While ß-alanine crystal appears from 62.7% RH for 2:1 and 59.4% RH for both 1:1 and 1:2 particles and lasts to driest state. On hydration, the DRH is 44.7%-75.2% for Na2CO3 with the OIR of 1:1 and 44.7%-69.0% for 1:2 mixture, and those of ß-alanine are 74.8% for 2:1 mixture and 68.9% for two others. After the first dehumidification-humidification, all the water contents decrease despite of constituent fraction. And at ~92% RH, the remaining water contents are 92%, 89% and 82% at ~92% RH, corresponding to OIR of 2:1, 1:1 and 1:2 mixed system, respectively.


Assuntos
Alanina/química , Carbonatos/química , Modelos Químicos , Espectroscopia de Infravermelho com Transformada de Fourier , Molhabilidade
5.
Food Chem ; 305: 125459, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31520919

RESUMO

In this study the elemental compositions of melanoidin formed at 160 °C from d-glucose (Glc) and l-alanine (Ala) as well as from fructosylalanine - the corresponding Amadori rearrangement product - were compared. Specific chemical bonds were probed by FTIR spectroscopy. This approach tackles the different chemical pathways for melanoidin formation via the Amadori rearrangement in contrast to the reaction from Glc/Ala. Melanoidins formed from fructosylalanine contain about twice as much nitrogen and therefore amino acid as compared to melanoidin from Glc/Ala and exhibit higher absorption in the UV/Vis. Consequently, melanoidins formed from Glc/Ala contain more sugar degradation products with lower absorption due to a smaller size of the conjugated double bond network.


Assuntos
Alanina/análogos & derivados , Alanina/química , Frutose/análogos & derivados , Frutose/química , Glucose/química , Polímeros/química , Frutose/síntese química , Espectroscopia de Ressonância Magnética , Reação de Maillard , Polímeros/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman
6.
Biochim Biophys Acta Mol Cell Res ; 1867(1): 118573, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31678591

RESUMO

Cytochrome c (Cyt c) released from mitochondria interacts with Apaf-1 to form the heptameric apoptosome, which initiates the caspase cascade to execute apoptosis. Although lysine residue at 72 (K72) of Cyt c plays an important role in the Cyt c-Apaf-1 interaction, the underlying mechanism of interaction between Cyt c and Apaf-1 is still not clearly defined. Here we identified multiple lysine residues including K72, which are also known to interact with ATP, to play a key role in Cyt c-Apaf-1 interaction. Mutation of these lysine residues abrogates the apoptosome formation causing inhibition of caspase activation. Using in-silico molecular docking, we have identified Cyt c-binding interface on Apaf-1. Although mutant Cyt c shows higher affinity for Apaf-1, the presence of Cyt c-WT restores the apoptosome activity. ATP addition modulates only mutant Cyt c binding to Apaf-1 but not WT Cyt c binding to Apaf-1. Using TCGA and cBioPortal, we identified multiple mutations in both Apaf-1 and Cyt c that are predicted to interfere with apoptosome assembly. We also demonstrate that transcript levels of various enzymes involved with dATP or ATP synthesis are increased in various cancers. Silencing of nucleotide metabolizing enzymes such as ribonucleotide reductase subunit M1 (RRM1) and ATP-producing glycolytic enzymes PKM2 attenuated ATP production and enhanced caspase activation. These findings suggest important role for lysine residues of Cyt c and nucleotides in the regulation of apoptosome-dependent apoptotic cell death as well as demonstrate how these mutations and nucleotides may have a pivotal role in human diseases such as cancer.


Assuntos
Apoptossomas/fisiologia , Citocromos c/química , Simulação de Acoplamento Molecular , Neoplasias/patologia , Nucleotídeos/química , Alanina/química , Alanina/genética , Substituição de Aminoácidos , Apoptossomas/química , Fator Apoptótico 1 Ativador de Proteases/química , Fator Apoptótico 1 Ativador de Proteases/metabolismo , Estudos de Casos e Controles , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/metabolismo , Células Cultivadas , Citocromos c/genética , Citocromos c/metabolismo , Feminino , Humanos , Lisina/química , Lisina/genética , Masculino , Modelos Moleculares , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Proteínas Mutantes/fisiologia , Neoplasias/genética , Neoplasias/metabolismo , Nucleotídeos/metabolismo , Células PC-3 , Ligação Proteica/genética , Mapeamento de Interação de Proteínas , Multimerização Proteica/genética , Transdução de Sinais/genética
7.
J Phys Chem Lett ; 10(24): 7878-7883, 2019 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-31794222

RESUMO

Local probes are indispensable to study protein structure and dynamics with site-specificity. The isonitrile functional group is a highly sensitive and H-bonding interaction-specific probe. Isonitriles exhibit large spectral shifts and transition dipole moment changes upon H-bonding while being weakly affected by solvent polarity. These unique properties allow a clear separation of distinct subpopulations of interacting species and an elucidation of their ultrafast dynamics with two-dimensional infrared (2D-IR) spectroscopy. Here, we apply 2D-IR to quantify the picosecond chemical exchange dynamics of solute-solvent complexes forming between isonitrile-derivatized alanine and fluorinated ethanol, where the degree of fluorination controls their H-bond-donating ability. We show that the molecules undergo faster exchange in the presence of more acidic H-bond donors, indicating that the exchange process is primarily dependent on the nature of solvent-solvent interactions. We foresee isonitrile as a highly promising probe for studying of H-bonds dynamics in the active site of enzymes.


Assuntos
Alanina/química , Técnicas Biossensoriais/métodos , Espectrofotometria Infravermelho/métodos , Simulação por Computador , Ligação de Hidrogênio , Cinética , Modelos Moleculares , Conformação Molecular , Transição de Fase , Solventes/química , Vibração
8.
Anticancer Res ; 39(12): 6531-6536, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31810918

RESUMO

BACKGROUND/AIM: Oral mucositis is a significant side effect in cancer treatment. In this study, we aimed to develop a rebamipide-containing film using chitosan and hydroxypropyl methylcellulose (HPMC) to efficiently treat oral mucositis. MATERIALS AND METHODS: A 0.1% (w/v) rebamipide aqueous solution, a 1.4% (w/v) chitosan aqueous solution containing Pluronic® F-127, and a 1.0% (w/v) HPMC aqueous solution were mixed and dried using a square silicon frame to form a film. Cumulative release ratios of rebamipide from sample films were measured in a phosphate buffer (pH 6.8) at 37°C. RESULTS: Chitosan suppressed the release of rebamipide from the film for up to 30 min. HPMC contributed to the sustained release of the film over a relatively long period of time and the maintenance of its shape. CONCLUSION: The combined use of chitosan and HPMC is suitable as a base material for rebamipide-containing films.


Assuntos
Alanina/análogos & derivados , Quitosana/química , Derivados da Hipromelose/química , Quinolonas/química , Estomatite/induzido quimicamente , Alanina/química , Antineoplásicos/efeitos adversos , Preparações de Ação Retardada , Humanos , Estomatite/tratamento farmacológico
9.
Phys Chem Chem Phys ; 22(1): 107-113, 2019 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-31807746

RESUMO

The non-enzymatic cleavage rates of amide bonds located in peptides in aqueous solution is pH-dependent and involves two distinct mechanisms: direct hydrolysis (herein termed "scission") and intramolecular aminolysis by the N-terminal amine (herein termed "backbiting"). While amide bond cleavage has been previously characterized using a variety of peptides, no systematic study has yet been reported addressing the effect of the pH on the interplay between the two amide bond cleavage pathways. In this study, the cleavage rates of the glycine dimer (GG), the glycine trimer (GGG), and the cyclic dimer (cGG), as well as the alanine trimer (AAA), were measured at pH 3, 5, 7, and 10 at 95 °C employing quantification based on 1H NMR. The distinct rate constants for scission and backbiting processes were obtained by solving the differential rate equations associated with the proposed kinetic model. Generalizations concerning the relative importance of the various amide bond cleavage pathways at pH 3, 5, 7, and 10 are presented. In particular, scission dominates at pH 10, while backbiting dominates at neutral pH. At the acidic pH of 3, both backbiting and scission are significant. The model of the reaction network, used in this work, enables the quantification of these multiple competing mechanisms and can be applied to longer peptides and to similar types of reaction networks.


Assuntos
Concentração de Íons de Hidrogênio , Peptídeos/química , Alanina/química , Amidas/química , Aminas/química , Glicina/química , Hidrólise , Cinética , Metionina/química , Estabilidade Proteica , Termodinâmica
10.
J Agric Food Chem ; 67(49): 13550-13557, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31721576

RESUMO

Enantioselectivity is usually ignored when assessing potential biochar-based methods of redressing pesticide contamination of soils. In this study, the effect of woodchip biochar (WBC) on the enantioselective dissipation of metalaxyl in soil and its uptake and translocation by lettuce were investigated. S-metalaxyl (T1/2 = 29.8 days) dissipated more quickly than R-metalaxyl (T1/2 = 36.4 days) in unamended soil. The addition of WBC to the soil decreased the dissipation rate and the enantioselectivity of metalaxyl. Metalaxyl distribution showed opposing enantioselectivity in lettuce, with roots and shoots showing preferences for R-metalaxyl and S-metalaxyl, respectively. Enrichment with WBC decreased the concentrations of metalaxyl and metalaxyl acid enantiomers in lettuce and reduced the ability of the shoots to transport the highly toxic R-metalaxyl from roots. This is the first study to provide evidence that amending soil with biochar affects the enantioselective uptake and translocation of a chiral pesticide.


Assuntos
Alanina/análogos & derivados , Carvão Vegetal/química , Recuperação e Remediação Ambiental/métodos , Alface/metabolismo , Praguicidas/química , Poluentes do Solo/química , Adsorção , Alanina/química , Alanina/metabolismo , Biodegradação Ambiental , Recuperação e Remediação Ambiental/instrumentação , Praguicidas/metabolismo , Raízes de Plantas/química , Raízes de Plantas/metabolismo , Poluentes do Solo/metabolismo
11.
Environ Sci Pollut Res Int ; 26(35): 35924-35934, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31707613

RESUMO

This study aimed to investigate changes in metalaxyl-M sorption-desorption capacity of soil following the addition of two types of amendments. Two biochars (BC) from grapevine pruning residues (BC-G) and spruce wood (BC-S) and two vermicomposts (VC) obtained vermicomposting digestates from a mixture of manure and olive mill wastewater (VC-M) and buffalo manure (VC-B) were used. Using a batch equilibration method, the materials and a silt loam soil non-amended or amended with each material at 2% (w/w) were interacted with the fungicide at a concentration of 2 mg L-1 for kinetics study and in the range 1-20 mg L-1 for sorption isotherms. Kinetics results showed that metalaxyl-M onto the amendments and non-amended soil followed preferentially a pseudo-second-order model, thus indicating a chemisorption process. Sorption isotherm data of the product on BC and VC fitted well the Freundlich equation, whereas those on non-amended and amended soil followed preferentially a linear model. The KFads values were 995.2, 788.5, 55.2, 52.1, 6.4, 6.0, 3.4, 2.6 and 1.5 L kg-1 for BC-G, BC-S, VC-M, VC-B, soil-BC-G, soil-BC-S, soil-VC-M, soil-VC-B and non-amended soil, respectively. Product desorption from each soil sample occurred to a lesser extent than sorption. Highly significant correlations (P < 0.005) were found between the values of sorption and desorption constants of all adsorbents and organic C content, thus confirming the prominent role of organic matter in the sorption process of metalaxyl-M.


Assuntos
Alanina/análogos & derivados , Carvão Vegetal/química , Fungicidas Industriais/química , Poluentes do Solo/química , Adsorção , Alanina/análise , Alanina/química , Fungicidas Industriais/análise , Esterco , Olea , Solo/química , Poluentes do Solo/análise , Madeira/química
12.
Chemistry ; 25(64): 14527-14531, 2019 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-31625640

RESUMO

A strategy for the continuous flow synthesis of angiotensin converting enzyme (ACE) inhibitors is described. An optimization effort guided by in situ IR analysis resulted in a general amide coupling approach facilitated by N-carboxyanhydride (NCA) activation that was further characterized by reaction kinetics analysis in batch. The three-step continuous process was demonstrated by synthesizing 8 different ACE inhibitors in up to 88 % yield with throughputs in the range of ≈0.5 g h-1 , all while avoiding both isolation of reactive intermediates and process intensive reaction conditions. The process was further developed by preparing enalapril, a World Health Organization (WHO) essential medicine, in an industrially relevant flow platform that scaled throughput to ≈1 g h-1 .


Assuntos
Alanina/química , Inibidores da Enzima Conversora de Angiotensina/química , Inibidores da Enzima Conversora de Angiotensina/síntese química , Enalapril/química , Cinética , Espectrofotometria Infravermelho
13.
Chem Pharm Bull (Tokyo) ; 67(10): 1164-1167, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31582637

RESUMO

Rebamipide is a therapeutic agent for gastric ulcers and chronic gastritis. Hypobromous acid (HOBr) is generated not only by eosinophils but also by neutrophils in the presence of bromide ions in the plasma. At inflammation sites, rebamipide may encounter and react with HOBr to generated various products. When rebamipide was incubated with reagent HOBr in potassium phosphate buffer at pH 4.7 and 37°C for 4 h, several products were generated. A major product was identified as 3-bromorebamipide, a novel compound. Rebamipide does not react with hypochlorous acid (HOCl). However, when rebamipide was incubated with HOCl in the presence of NaBr, 3-bromorebamipide was generated in a dose-dependent manner, probably because of formation of HOBr. These results suggest that 3-bromorebamipide may generate from rebamipide at inflammation sites in humans.


Assuntos
Alanina/análogos & derivados , Bromatos/química , Quinolonas/química , Alanina/química , Humanos , Ácido Hipocloroso/química , Estrutura Molecular
14.
Analyst ; 144(19): 5724-5737, 2019 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-31486453

RESUMO

In order to explore the properties of any species in solution, the actual, i.e. equilibrium concentration of the free species should be taken into account. Researchers have not paid attention to the deprotonation equilibrium between HSO4- and SO42- while probing bisulfate ion. In this study, we have addressed this concern and developed two zwitterions, CG (coumarin-integrated glycine) and CA (coumarin-integrated alanine), for the selective detection of HSO4- at a picomolar level (50 to 325 pM) with very high binding affinity (∼108 M-1) in pure water at physiological pH. The principle of HSO4- recognition was established via UV-vis and fluorescence techniques. DFT calculations suggested that the H-bonding interactions between the probes and HSO4- are the driving force for this unforeseen selectivity. The membrane penetration ability and nontoxicity of CG/CA enable them to function as staining agents in living brine shrimps and bacteria. The use of these probes for the estimation of HSO4- in various day-to-day edible foods and drugs along with urine samples is unprecedented. The significance and novelty of this study lies in the application and development of assays for estimating bisulfate in several real-world samples that are predominantly aqueous in nature, which are the first of their kind.


Assuntos
Cumarínicos/química , Corantes Fluorescentes/química , Imagem Óptica/métodos , Plantas Comestíveis/química , Sulfatos/análise , Alanina/química , Animais , Artemia/química , Bactérias/química , Cães , Análise de Alimentos , Glicina/química , Humanos , Concentração de Íons de Hidrogênio , Limite de Detecção , Permeabilidade , Sensibilidade e Especificidade , Sulfatos/urina , Água/química
15.
J Pept Sci ; 25(8): e3177, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31317614

RESUMO

Thermal treatment of short-chain oligopeptides is able to initiate the process of their self-assembly with the formation of organic nanostructures with unique properties. On the other hand, heating can lead to a chemical reaction with the formation of new substances with specific properties and ability to form structures with different morphology. Therefore, in order to have a desired process, researcher needs to find its temperature range. In the present work, cyclization of L -isoleucyl-L -alanine dipeptide in the solid state upon heating was studied. Kinetic parameters of this reaction were estimated within the approaches of the nonisothermal kinetics. The correlation between side chain structure of dipeptides and temperature of their cyclization in the solid state was found for the first time. This correlation may be used to predict the temperature, at which dipeptide self-assembly changes to chemical reaction. The differences in self-assembly of linear and cyclic dipeptides were demonstrated using atomic force microscopy. The effect of dipeptide concentration in a source solution and an organic solvent used on self-assembly of dipeptides was shown. The new information obtained on the thermal properties and self-assembly of linear and cyclic forms of L -isoleucyl-L -alanine may be useful for the design of new nanomaterials based on oligopeptides, as well as for the synthesis of cyclic oligopeptides.


Assuntos
Alanina/química , Dipeptídeos/síntese química , Isoleucina/química , Temperatura , Ciclização , Dipeptídeos/química , Cromatografia Gasosa-Espectrometria de Massas , Cinética , Conformação Molecular
16.
Org Biomol Chem ; 17(28): 6777-6781, 2019 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-31268077

RESUMO

Herein, we design and synthesize a series of photoactivatable ß-diarylsydnone-l-alanines (DASAs), which have excellent photo-reactivity with high fluorescence turn-on toward alkenes in a biocompatible environment. The environmental sensing properties of the resulting fluorescent pyrazoline-alanine facilitate its probing capability. By introducing the DASA residue on the side chain of linear peptides, the macrocyclic peptides resulting from the in situ photo-cyclization toward the alkene residue exhibited fluorogenic translocation through live cell membranes.


Assuntos
Alanina/química , Corantes Fluorescentes/química , Peptídeos/síntese química , Células A549 , Alanina/análogos & derivados , Alanina/síntese química , Membrana Celular/química , Química Click , Ciclização , Corantes Fluorescentes/síntese química , Humanos , Imagem Óptica , Peptídeos/química , Processos Fotoquímicos
17.
Int J Mol Sci ; 20(13)2019 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-31269680

RESUMO

Much of the experimental data, especially in life sciences, is considered to be useless if it demonstrates a large standard deviation from the mean value. The Renaissance distribution, as presented in this study, allows one to extract true values from such statistical data with large noise. To obtain proof of the Renaissance distribution, high-throughput synthesis of deep substitutions for a target amino acid sequence was performed, and the known epitope was identified in assay with human serum antibodies. In addition, the Renaissance distribution was shown to approach the epitope affinity maturation by the deep alanine substitution. The Renaissance distribution may have an impact in the development of novel specific drugs.


Assuntos
Alanina/genética , Substituição de Aminoácidos , Peptídeos/genética , Alanina/química , Sequência de Aminoácidos , Epitopos/química , Epitopos/genética , Humanos , Modelos Moleculares , Peptídeos/química , Análise Serial de Proteínas , Distribuições Estatísticas , Processos Estocásticos
18.
Molecules ; 24(13)2019 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-31288444

RESUMO

Recently, we have found that calcium binding proteins of the EF-hand superfamily (i.e., a large family of proteins containing helix-loop-helix calcium binding motif or EF-hand) contain two types of conserved clusters called cluster I ('black' cluster) and cluster II ('grey' cluster), which provide a supporting scaffold for the Ca2+ binding loops and contribute to the hydrophobic core of the EF-hand domains. Cluster I is more conservative and mostly incorporates aromatic amino acids, whereas cluster II includes a mix of aromatic, hydrophobic, and polar amino acids of different sizes. Recoverin is EF-hand Ca2+-binding protein containing two 'black' clusters comprised of F35, F83, Y86 (N-terminal domain) and F106, E169, F172 (C-terminal domain) as well as two 'gray' clusters comprised of F70, Q46, F49 (N-terminal domain) and W156, K119, V122 (C-terminal domain). To understand a role of these residues in structure and function of human recoverin, we sequentially substituted them for alanine and studied the resulting mutants by a set of biophysical methods. Under metal-free conditions, the 'black' clusters mutants (except for F35A and E169A) were characterized by an increase in the α-helical content, whereas the 'gray' cluster mutants (except for K119A) exhibited the opposite behavior. By contrast, in Ca2+-loaded mutants the α-helical content was always elevated. In the absence of calcium, the substitutions only slightly affected multimerization of recoverin regardless of their localization (except for K119A). Meanwhile, in the presence of calcium mutations in N-terminal domain of the protein significantly suppressed this process, indicating that surface properties of Ca2+-bound recoverin are highly affected by N-terminal cluster residues. The substitutions in C-terminal clusters generally reduced thermal stability of recoverin with F172A ('black' cluster) as well as W156A and K119A ('gray' cluster) being the most efficacious in this respect. In contrast, the mutations in the N-terminal clusters caused less pronounced differently directed changes in thermal stability of the protein. The substitutions of F172, W156, and K119 in C-terminal domain of recoverin together with substitution of Q46 in its N-terminal domain provoked significant but diverse changes in free energy associated with Ca2+ binding to the protein: the mutant K119A demonstrated significantly improved calcium binding, whereas F172A and W156A showed decrease in the calcium affinity and Q46A exhibited no ion coordination in one of the Ca2+-binding sites. The most of the N-terminal clusters mutations suppressed membrane binding of recoverin and its inhibitory activity towards rhodopsin kinase (GRK1). Surprisingly, the mutant W156A aberrantly activated rhodopsin phosphorylation regardless of the presence of calcium. Taken together, these data confirm the scaffolding function of several cluster-forming residues and point to their critical role in supporting physiological activity of recoverin.


Assuntos
Recoverina/química , Recoverina/metabolismo , Alanina/química , Motivos de Aminoácidos , Substituição de Aminoácidos , Cálcio/metabolismo , Receptor Quinase 1 Acoplada a Proteína G/metabolismo , Humanos , Interações Hidrofóbicas e Hidrofílicas , Cinética , Modelos Moleculares , Mutação , Fosforilação , Ligação Proteica , Recoverina/genética , Rodopsina/metabolismo
19.
Chemistry ; 25(55): 12698-12702, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31361053

RESUMO

We report the late-stage chemical modification of ribosomally synthesized and post-translationally modified peptides (RIPPs) by Diels-Alder cycloadditions to naturally occurring dehydroalanines. The tail region of the thiopeptide thiostrepton could be modified selectively and efficiently under microwave heating and transition-metal-free conditions. The Diels-Alder adducts were isolated and the different site- and endo/exo isomers were identified by 1D/2D 1 H NMR. Via efficient modification of the thiopeptide nosiheptide and the lanthipeptide nisin Z the generality of the method was established. Minimum inhibitory concentration (MIC) assays of the purified thiostrepton Diels-Alder products against thiostrepton-susceptible strains displayed high activities comparable to that of native thiostrepton. These Diels-Alder products were also subjected successfully to inverse-electron-demand Diels-Alder reactions with a variety of functionalized tetrazines, demonstrating the utility of this method for labeling of RiPPs.


Assuntos
Alanina/análogos & derivados , Peptídeos/síntese química , Ribossomos/metabolismo , Alanina/síntese química , Alanina/química , Reação de Cicloadição , Peptídeos/química , Processamento de Proteína Pós-Traducional , Ribossomos/química
20.
Chirality ; 31(9): 628-634, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31334578

RESUMO

Based on a Cambridge Structural Database (CSD) search, a meta-analysis of 116 structures of alanine H3 NCα H(CH3 )C'(O)O and its derivatives H3 NCα H(CH3 )C'(O)O(H/R/M), protonated, esterified, or coordinated at the carboxylic group, shows that in the first step of a chirality chain, the L configuration at Cα induces (M) and (P) conformations with respect to rotation around the central C'─Cα bond. In the second step, the (M) and (P) conformations selectively distort the planar carboxylic group Cα C'(Ocis )Otrans to asymmetric flat (R) and (S) tetrahedra. High diastereoselectivities are caused by the two players attraction N…Ocis and repulsion Otrans …CMe , which work together in (L,M,R) configurations but against each other in (L,P,S) configurations.


Assuntos
Alanina/química , Amidas/química , Ligação de Hidrogênio , Conformação Molecular , Estereoisomerismo
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