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1.
Methods Mol Biol ; 2266: 239-259, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33759131

RESUMO

Molecular dynamics simulations can now routinely access the microsecond timescale, making feasible direct sampling of ligand association events. While Markov State Model (MSM) approaches offer a useful framework for analyzing such trajectory data to gain insight into binding mechanisms, accurate modeling of ligand association pathways and kinetics must be done carefully. We describe methods and good practices for constructing MSMs of ligand binding from unbiased trajectory data and discuss how to use time-lagged independent component analysis (tICA) to build informative models, using as an example recent simulation work to model the binding of phenylalanine to the regulatory ACT domain dimer of phenylalanine hydroxylase. We describe a variety of methods for estimating association rates from MSMs and discuss how to distinguish between conformational selection and induced-fit mechanisms using MSMs. In addition, we review some examples of MSMs constructed to elucidate the mechanisms by which p53 transactivation domain (TAD) and related peptides bind the oncoprotein MDM2.


Assuntos
Cadeias de Markov , Simulação de Dinâmica Molecular , Fenilalanina Hidroxilase/química , Fenilalanina/química , Proteínas Proto-Oncogênicas c-mdm2/química , Software , Proteína Supressora de Tumor p53/química , Cinética , Ligantes , Ligação Proteica , Domínios Proteicos , Estrutura Terciária de Proteína
2.
Biochim Biophys Acta Proteins Proteom ; 1869(1): 140543, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32966894

RESUMO

Cold-adapted enzymes maintain correct conformation at their active sites despite their intrinsically flexible structures. The psychrophilic Arctic bacterium Sphingomonas sp. PAMC 26621 has two glucose 6-phosphate dehydrogenase (G6PD) isozymes, SpG6PD1 involved in the Entner-Doudoroff pathway and SpG6PD2 in the oxidative pentose phosphate pathway. Structural modeling of SpG6PD1 showed that the hydroxyl group of Tyr177 participates in substrate binding by forming a hydrogen bond with the phosphate group of glucose 6-phosphate, whereas in SpG6PD2, a Phe residue is present in the corresponding position of Tyr177. In this study, we investigated how subtle differences in aromatic residues in the substrate-binding pocket of SpG6PD1 affect enzymatic activity and stability. Mutations of Tyr177 to Ala, His, Phe, and Trp caused increases in the rigidity of the SpG6PD1 structure. Particularly, mutants Y177F and Y177W showed increased thermal stabilities compared to wild-type (WT) but 3- and 15-fold lower catalytic efficiencies, respectively. However, mutants Y177A and Y177H became heat-labile at moderate temperatures. These results indicate that an aromatic residue (Tyr or Phe) is necessary for the substrate-binding pocket of SpG6PD1; Tyr with its hydroxyl group is preferred for enzymatic activity, whereas the more hydrophobic Phe is preferred for thermal stability. Substitutions of bulky Trp for Tyr or Phe at this position resulted in substantial loss of activity. Our study suggests that delicate adjustment of aromatic residues can regulate the activity and stability of psychrophilic G6PD isozymes involved in different metabolic pathways.


Assuntos
Proteínas de Bactérias/química , Glucose-6-Fosfato/química , Glucosefosfato Desidrogenase/química , Fenilalanina/química , Sphingomonas/química , Tirosina/química , Adaptação Fisiológica , Substituição de Aminoácidos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Sítios de Ligação , Biocatálise , Temperatura Baixa , Expressão Gênica , Glucose-6-Fosfato/metabolismo , Glucosefosfato Desidrogenase/genética , Glucosefosfato Desidrogenase/metabolismo , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Cinética , Simulação de Acoplamento Molecular , Mutagênese Sítio-Dirigida , Fenilalanina/metabolismo , Ligação Proteica , Conformação Proteica em alfa-Hélice , Conformação Proteica em Folha beta , Domínios e Motivos de Interação entre Proteínas , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Sphingomonas/enzimologia , Especificidade por Substrato , Triptofano/química , Triptofano/metabolismo , Tirosina/metabolismo
3.
J Chromatogr A ; 1636: 461792, 2021 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-33340747

RESUMO

Chiral metal-organic cages (MOCs) are a new type of porous materials with unique molecular recognition ability, which have received research attention as a chiral stationary phase (CSP) for gas chromatography (GC). Herein, we report the detailed investigation of a chiral MOC ([Cu12(LPA)12(H2O)12], PA = L-phenylalanine, MOC-PA) as a novel stationary phase for GC separations. The MOC-PA capillary column exhibited a high-resolution performance for a wide range of analytes, including n-alkanes, n-alcohols, esters, aromatic compounds and the Grob mixture, positional isomers and racemates. In particular, MOC-PA coated column displayed good resolution and performance for amino acid derivatives. Moreover, the MOC-PA column showed excellent separation repeatability and reproducibility. The relative standard deviation (RSD) values for the retention times were in the range of 0.16-0.30% for run to run (n = 3), 0.31-0.77% for day-to-day (n = 3), and 3.6-4.7% for column-to-column (n = 3), respectively. The experimental results showed that MOC-PA had great potential as a GC stationary phase.


Assuntos
Cromatografia Gasosa/métodos , Metais/química , Compostos Orgânicos/química , Álcoois/química , Alcanos/química , Ésteres/química , Fenilalanina/química , Reprodutibilidade dos Testes , Espectroscopia de Infravermelho com Transformada de Fourier , Estereoisomerismo , Termogravimetria , Difração de Raios X
4.
Nat Commun ; 11(1): 4914, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-33004788

RESUMO

Oxepinamides are derivatives of anthranilyl-containing tripeptides and share an oxepin ring and a fused pyrimidinone moiety. To the best of our knowledge, no studies have been reported on the elucidation of an oxepinamide biosynthetic pathway and conversion of a quinazolinone to a pyrimidinone-fused 1H-oxepin framework by a cytochrome P450 enzyme in fungal natural product biosynthesis. Here we report the isolation of oxepinamide F from Aspergillus ustus and identification of its biosynthetic pathway by gene deletion, heterologous expression, feeding experiments, and enzyme assays. The nonribosomal peptide synthase (NRPS) OpaA assembles the quinazolinone core with D-Phe incorporation. The cytochrome P450 enzyme OpaB catalyzes alone the oxepin ring formation. The flavoenzyme OpaC installs subsequently one hydroxyl group at the oxepin ring, accompanied by double bond migration. The epimerase OpaE changes the D-Phe residue back to L-form, which is essential for the final methylation by OpaF.


Assuntos
Amidas/metabolismo , Aspergillus/enzimologia , Proteínas Fúngicas/metabolismo , Oxepinas/metabolismo , Amidas/química , Amidas/isolamento & purificação , Aspergillus/genética , Vias Biossintéticas , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Ensaios Enzimáticos , Proteínas Fúngicas/genética , Hidroxilação , Isomerismo , Metilação , Oxepinas/química , Oxepinas/isolamento & purificação , Peptídeo Sintases/genética , Peptídeo Sintases/metabolismo , Fenilalanina/química , Fenilalanina/metabolismo , Proteína O-Metiltransferase/genética , Proteína O-Metiltransferase/metabolismo , Quinazolinonas/metabolismo , Racemases e Epimerases/genética , Racemases e Epimerases/metabolismo
5.
PLoS One ; 15(10): e0240045, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33017434

RESUMO

BACKGROUND: Enteral nutrition (EN) is a ubiquitous intervention in ICU patients but there is uncertainty regarding the optimal dose, timing and importance for patient-centered outcomes during critical illness. Our research group has previously found an improved protein balance during normocaloric versus hypocaloric parenteral nutrition in neurosurgical ICU patients. We now wanted to investigate if this could be demonstrated in a general ICU population with established enteral feeding, including patients on renal replacement therapy. METHODS: Patients with EN >80% of energy target as determined by indirect calorimetry were randomized to or 50% or 100% of current EN rate. After 24 hours, whole-body protein kinetics were determined by enteral and parenteral stable isotope tracer infusions. Treatment allocation was then switched, and tracer investigations repeated 24 hours later in a crossover design with patients serving as their own controls. RESULTS: Six patients completed the full protocol. During feeding with 100% EN all patients received >1.2 g/kg/day of protein. Mean whole-body protein balance increased from -6.07 to 2.93 µmol phenylalanine/kg/h during 100% EN as compared to 50% (p = 0.044). The oxidation rate of phenylalanine was unaltered (p = 0.78). CONCLUSIONS: It is possible to assess whole-body protein turnover using a stable isotope technique in critically ill patients during enteral feeding and renal replacement therapy. Our results also suggest a better whole-body protein balance during full dose as compared to half dose EN. As the sample size was smaller than anticipated, this finding should be confirmed in larger studies.


Assuntos
Metabolismo Energético , Nutrição Enteral/métodos , Proteínas/metabolismo , Adulto , Idoso , Isótopos de Carbono/química , Estado Terminal , Estudos Cross-Over , Ingestão de Energia , Feminino , Humanos , Unidades de Terapia Intensiva , Marcação por Isótopo , Cinética , Masculino , Pessoa de Meia-Idade , Nutrição Parenteral , Fenilalanina/química , Fenilalanina/metabolismo , Contagem Corporal Total/métodos
6.
Nat Commun ; 11(1): 4160, 2020 08 19.
Artigo em Inglês | MEDLINE | ID: mdl-32814772

RESUMO

Ghrelin is a gastric peptide hormone with important physiological functions. The unique feature of ghrelin is its Serine 3 acyl-modification, which is essential for ghrelin's activity. However, it remains to be elucidated why the acyl-modification of ghrelin is necessary for activity. To address these questions, we solved the crystal structure of the ghrelin receptor bound to antagonist. The ligand-binding pocket of the ghrelin receptor is bifurcated by a salt bridge between E124 and R283. A striking feature of the ligand-binding pocket of the ghrelin receptor is a wide gap (crevasse) between the TM6 and TM7 bundles that is rich in hydrophobic amino acids, including a cluster of phenylalanine residues. Mutagenesis analyses suggest that the interaction between the gap structure and the acyl acid moiety of ghrelin may participate in transforming the ghrelin receptor into an active conformation.


Assuntos
Grelina/metabolismo , Fenilalanina/metabolismo , Receptores de Grelina/metabolismo , Animais , Sítios de Ligação/genética , Células CHO , Cricetinae , Cricetulus , Cristalografia por Raios X , Grelina/química , Grelina/genética , Células HEK293 , Humanos , Ligantes , Camundongos Endogâmicos MRL lpr , Mutagênese Sítio-Dirigida , Fenilalanina/química , Fenilalanina/genética , Ligação Proteica , Conformação Proteica , Receptores de Grelina/antagonistas & inibidores , Receptores de Grelina/genética , Células Sf9 , Spodoptera
7.
Acta Crystallogr C Struct Chem ; 76(Pt 4): 328-345, 2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32229714

RESUMO

Recently, fluorenylmethoxycarbonyl (Fmoc) amino acids (e.g. Fmoc-tyrosine or Fmoc-phenylalanine) have attracted growing interest in biomedical research and industry, with special emphasis directed towards the design and development of novel effective hydrogelators, biomaterials or therapeutics. With this in mind, a systematic knowledge of the structural and supramolecular features in recognition of those properties is essential. This work is the first comprehensive summary of noncovalent interactions combined with a library of supramolecular synthon patterns in all crystal structures of amino acids with the Fmoc moiety reported so far. Moreover, a new Fmoc-protected amino acid, namely, 2-{[(9H-fluoren-9-ylmethoxy)carbonyl](methyl)amino}-3-{4-[(2-hydroxypropan-2-yl)oxy]phenyl}propanoic acid or N-fluorenylmethoxycarbonyl-O-tert-butyl-N-methyltyrosine, Fmoc-N-Me-Tyr(t-Bu)-OH, C29H31NO5, was successfully synthesized and the structure of its unsolvated form was determined by single-crystal X-ray diffraction. The structural, conformational and energy landscape was investigated in detail by combined experimental and in silico approaches, and further compared to N-Fmoc-phenylalanine [Draper et al. (2015). CrystEngComm, 42, 8047-8057]. Geometries were optimized by the density functional theory (DFT) method either in vacuo or in solutio. The polarizable conductor calculation model was exploited for the evaluation of the hydration effect. Hirshfeld surface analysis revealed that H...H, C...H/H...C and O...H/H...O interactions constitute the major contributions to the total Hirshfeld surface area in all the investigated systems. The molecular electrostatic potentials mapped over the surfaces identified the electrostatic complementarities in the crystal packing. The prediction of weak hydrogen-bonded patterns via Full Interaction Maps was computed. Supramolecular motifs formed via C-H...O, C-H...π, (fluorenyl)C-H...Cl(I), C-Br...π(fluorenyl) and C-I...π(fluorenyl) interactions are observed. Basic synthons, in combination with the Long-Range Synthon Aufbau Modules, further supported by energy-framework calculations, are discussed. Furthermore, the relevance of Fmoc-based supramolecular hydrogen-bonding patterns in biocomplexes are emphasized, for the first time.


Assuntos
Aminoácidos/química , Fluorenos/síntese química , Metiltirosinas/química , Fenilalanina/química , Aminoácidos/síntese química , Simulação por Computador , Cristalografia por Raios X , Fluorenos/química , Ligação de Hidrogênio , Conformação Molecular , Inquéritos e Questionários
8.
Nat Chem Biol ; 16(6): 702-709, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32203413

RESUMO

When the primitive translation system first emerged in the hypothetical RNA world, ribozymes could have been responsible for aminoacylation. Given that naturally occurring T-box riboswitches selectively sense the aminoacylation status of cognate tRNAs, we introduced a domain of random sequence into a T-box-tRNA conjugate and isolated ribozymes that were self-aminoacylating on the 3'-terminal hydroxyl group. One of them, named Tx2.1, recognizes the anticodon and D-loop of tRNA via interaction with its stem I domain, similarly to the parental T-box, and selectively charges N-biotinyl-L-phenylalanine (Bio-lPhe) onto the 3' end of the cognate tRNA in trans. We also demonstrated the ribosomal synthesis of a Bio-lPhe-initiated peptide in a Tx2.1-coupled in vitro translation system, in which Tx2.1 catalyzed specific tRNA aminoacylation in situ. This suggests that such ribozymes could have coevolved with a primitive translation system in the RNA world.


Assuntos
RNA Catalítico/genética , RNA Catalítico/metabolismo , Riboswitch/genética , Aminoacilação de RNA de Transferência/efeitos dos fármacos , Bacillus subtilis/enzimologia , Sequência de Bases , Biotina/química , Domínio Catalítico , Biblioteca Gênica , Modelos Genéticos , Modelos Moleculares , Mutação , Conformação de Ácido Nucleico , Fenilalanina/química , Ligação Proteica , Estreptavidina/metabolismo
9.
Biomater Sci ; 8(7): 2031-2039, 2020 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-32083626

RESUMO

Antimicrobial peptides (AMPs) as biocides are of great interest because they have the ability to combat antibiotic resistance. Normally, natural AMPs need to be rationally designed or modified for practical use as an antibiotic. Here, a novel AMP, termed FF8, which is a cationic octapeptide composed of arginine, lysine, and phenylalanine, was designed. The FF8 was found to self-assemble into nanofibers when induced by a negatively charged lipid membrane or pH is above 9.4. The fibers on the membrane broke the lipid membrane, forming pores and significantly reducing its fluidity. FF8 also exhibited enhanced antibacterial activity by significantly increasing the permeability of the inner and outer membranes of Escherichia coli (E. coli) and maintaining the pores of the inner membrane of cells, which caused continuous membrane leakage. Because of its high antibacterial activity, cytocompatibility, and cost-effectiveness, FF8 is a promising antibacterial material.


Assuntos
Peptídeos Catiônicos Antimicrobianos/farmacologia , Arginina/química , Escherichia coli/efeitos dos fármacos , Lisina/química , Fenilalanina/química , Peptídeos Catiônicos Antimicrobianos/síntese química , Peptídeos Catiônicos Antimicrobianos/química , Membrana Celular/efeitos dos fármacos , Permeabilidade da Membrana Celular/efeitos dos fármacos , Farmacorresistência Bacteriana/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Testes de Sensibilidade Microbiana , Estrutura Molecular , Nanofibras
10.
Molecules ; 25(4)2020 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-32075114

RESUMO

The content of selected major nitrogen compounds including nucleosides and their derivatives was evaluated in 75 samples of seven varieties of honey (heather, buckwheat, black locust, goldenrod, canola, fir, linden) by targeted ultra-high performance liquid chromatography-diode array detector - high-resolution quadrupole time-of-flight mass spectrometry (UHPLC-DAD-QqTOF-MS) and determined by UHPLC-DAD. The honey samples contained nucleosides, nucleobases and their derivatives (adenine: 8.9 to 18.4 mg/kg, xanthine: 1.2 to 3.3 mg/kg, uridine: 17.5 to 51.2 mg/kg, guanosine: 2.0 to 4.1 mg/kg; mean amounts), aromatic amino acids (tyrosine: 7.8 to 263.9 mg/kg, phenylalanine: 9.5 to 64.1 mg/kg; mean amounts). The amounts of compounds significantly differed between some honey types. For example, canola honey contained a much lower amount of uridine (17.5 ± 3.9 mg/kg) than black locust where it was most abundant (51.2 ± 7.8 mg/kg). The presence of free nucleosides and nucleobases in different honey varieties is reported first time and supports previous findings on medicinal activities of honey reported in the literature as well as traditional therapy and may contribute for their explanation. This applies, e.g., to the topical application of honey in herpes infections, as well as its beneficial activity on cognitive functions as nootropic and neuroprotective, in neuralgia and is also important for the understanding of nutritional values of honey.


Assuntos
Aminoácidos Aromáticos/química , Fagopyrum/química , Mel , Compostos de Nitrogênio/química , Adenina/química , Cromatografia Líquida de Alta Pressão , Espectrometria de Massas , Nucleosídeos/química , Fenilalanina/química , Tilia/química , Tirosina/química , Uridina/química , Xantina/química
11.
Science ; 367(6478): 694-699, 2020 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-32029630

RESUMO

Prion-like domains (PLDs) can drive liquid-liquid phase separation (LLPS) in cells. Using an integrative biophysical approach that includes nuclear magnetic resonance spectroscopy, small-angle x-ray scattering, and multiscale simulations, we have uncovered sequence features that determine the overall phase behavior of PLDs. We show that the numbers (valence) of aromatic residues in PLDs determine the extent of temperature-dependent compaction of individual molecules in dilute solutions. The valence of aromatic residues also determines full binodals that quantify concentrations of PLDs within coexisting dilute and dense phases as a function of temperature. We also show that uniform patterning of aromatic residues is a sequence feature that promotes LLPS while inhibiting aggregation. Our findings lead to the development of a numerical stickers-and-spacers model that enables predictions of full binodals of PLDs from their sequences.


Assuntos
Ribonucleoproteína Nuclear Heterogênea A1/química , Transição de Fase , Fenilalanina/química , Príons/química , Tirosina/química , Sequência de Aminoácidos , Espectroscopia de Ressonância Magnética , Domínios Proteicos , Espalhamento a Baixo Ângulo , Difração de Raios X
12.
Chem Asian J ; 15(7): 1018-1021, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32017396

RESUMO

Benzyl alcohol is a naturally occurring aromatic alcohol and has been widely used in the cosmetics and flavor/fragrance industries. The whole-cell biotransformation for synthesis of benzyl alcohol directly from bio-based L-phenylalanine (L-Phe) was herein explored using an artificial enzyme cascade in Escherichia coli. Benzaldehyde was first produced from L-Phe via four heterologous enzymatic steps that comprises L-amino acid deaminase (LAAD), hydroxymandelate synthase (HmaS), (S)-mandelate dehydrogenase (SMDH) and benzoylformate decarboxylase (BFD). The subsequent reduction of benzaldehyde to benzyl alcohol was achieved by a broad substrate specificity phenylacetaldehyde reductase (PAR) from Solanum lycopersicum. We found the designed enzyme cascade could efficiently convert L-Phe into benzyl alcohol with conversion above 99%. In addition, we also examined L-tyrosine (L-Tyr) and m-fluoro-phenylalanine (m-f-Phe) as substrates, the cascade biotransformation could also efficiently produce p-hydroxybenzyl alcohol and m-fluoro-benzyl alcohol. In summary, the developed biocatalytic pathway has great potential to produce various high-valued fine chemicals.


Assuntos
Álcoois Benzílicos/síntese química , Biotransformação , Benzaldeídos/química , Biocatálise , Vias Biossintéticas , Escherichia coli/metabolismo , Fenilalanina/química , Especificidade por Substrato
13.
J Enzyme Inhib Med Chem ; 35(1): 610-621, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32013633

RESUMO

Cyclic imides containing 3-benzenesulfonamide, oxime, and ß-phenylalanine derivatives were synthesised and evaluated to elucidate their in vivo anti-inflammatory and ulcerogenic activity and in vitro cytotoxic effects. Most active anti-inflammatory agents were subjected to in vitro COX-1/2 inhibition assay. 3-Benzenesulfonamides (2-4, and 9), oximes (11-13), and ß-phenylalanine derivative (18) showed potential anti-inflammatory activities with 71.2-82.9% oedema inhibition relative to celecoxib and diclofenac (85.6 and 83.4%, respectively). Most active cyclic imides 4, 9, 12, 13, and 18 possessed ED50 of 35.4-45.3 mg kg-1 relative to that of celecoxib (34.1 mg kg-1). For the cytotoxic evaluation, the selected derivatives 2-6 and 8 exhibited weak positive cytotoxic effects (PCE = 2/59-5/59) at 10 µM compared to the standard drug, imatinib (PCE = 20/59). Cyclic imides bearing 3-benzenesulfonamide (2-5, and 9), acetophenone oxime (11-14, 18, and 19) exhibited high selectivity against COX-2 with SI > 55.6-333.3 relative to that for celecoxib [SI > 387.6]. ß-Phenylalanine derivatives 21-24 and 28 were non-selective towards COX-1/2 isozymes as indicated by their SI of 0.46-0.68.


Assuntos
Anti-Inflamatórios não Esteroides/farmacologia , Antineoplásicos/farmacologia , Inibidores de Ciclo-Oxigenase/farmacologia , Imidas/farmacologia , Oximas/farmacologia , Fenilalanina/farmacologia , Sulfonamidas/farmacologia , Animais , Anti-Inflamatórios não Esteroides/síntese química , Anti-Inflamatórios não Esteroides/química , Antineoplásicos/síntese química , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Ciclo-Oxigenase 1/metabolismo , Ciclo-Oxigenase 2/metabolismo , Inibidores de Ciclo-Oxigenase/síntese química , Inibidores de Ciclo-Oxigenase/química , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Edema/tratamento farmacológico , Humanos , Imidas/química , Simulação de Acoplamento Molecular , Estrutura Molecular , Oximas/química , Fenilalanina/química , Ratos , Relação Estrutura-Atividade , Sulfonamidas/química
14.
Sci Adv ; 6(4): eaaz1722, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-32010792

RESUMO

In the current clinical boron neutron capture therapy (BNCT), p-boronophenylalanine (BPA) has been the most powerful drug owing to its ability to accumulate selectively within cancers through cancer-related amino acid transporters including LAT1. However, the therapeutic success of BPA has been sometimes compromised by its unfavorable efflux from cytosol due to their antiport mechanism. Here, we report that poly(vinyl alcohol) (PVA) can form complexes with BPA through reversible boronate esters in aqueous solution, and the complex termed PVA-BPA can be internalized into cancer cells through LAT1-mediated endocytosis, thereby enhancing cellular uptake and slowing the untoward efflux. In in vivo study, compared with clinically used fructose-BPA complexes, PVA-BPA exhibited efficient tumor accumulation and prolonged tumor retention with quick clearance from bloodstream and normal organs. Ultimately, PVA-BPA showed critically enhanced antitumor activity in BNCT. The facile technique proposed in this study offers an approach for drug delivery focusing on drug metabolism.


Assuntos
Compostos de Boro/farmacologia , Terapia por Captura de Nêutron de Boro , Metabolismo Energético/efeitos dos fármacos , Fenilalanina/análogos & derivados , Álcool de Polivinil/farmacologia , Radiossensibilizantes/farmacologia , Animais , Compostos de Boro/química , Compostos de Boro/farmacocinética , Linhagem Celular Tumoral , Modelos Animais de Doenças , Sinergismo Farmacológico , Humanos , Espectrometria de Massas , Camundongos , Neoplasias/terapia , Fenilalanina/química , Fenilalanina/farmacocinética , Fenilalanina/farmacologia , Álcool de Polivinil/química , Álcool de Polivinil/farmacocinética , Radiossensibilizantes/química , Radiossensibilizantes/farmacocinética , Transdução de Sinais/efeitos dos fármacos , Distribuição Tecidual , Ensaios Antitumorais Modelo de Xenoenxerto
15.
Chem Commun (Camb) ; 56(25): 3641-3644, 2020 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-32107512

RESUMO

Site-specific placement of unnatural amino acids, particularly those responsive to light, offers an elegant approach to control protein function and capture their fleeting 'interactome'. Herein, we have resurrected 4-(trifluoromethyldiazirinyl)-phenylalanine, an underutilized photo-crosslinker, by introducing several key features including easy synthetic access, site-specific incorporation by 'privileged' synthetases and superior crosslinking efficiency, to develop photo-crosslinkable bromodomains suitable for 'interactome' profiling.


Assuntos
Aminoácidos/metabolismo , Aminoacil-tRNA Sintetases/metabolismo , Reagentes para Ligações Cruzadas/metabolismo , Fenilalanina/metabolismo , Engenharia de Proteínas , Aminoácidos/química , Aminoacil-tRNA Sintetases/química , Reagentes para Ligações Cruzadas/síntese química , Reagentes para Ligações Cruzadas/química , Estrutura Molecular , Fenilalanina/análogos & derivados , Fenilalanina/química , Processos Fotoquímicos
16.
Nanoscale ; 12(5): 3038-3049, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-31971529

RESUMO

Molecular self-assembly is a bottom-up approach to fabricate novel supramolecular structures. While the structural diversity obtained by the use of a single type of building block is limited, coassembly of different peptides has recently evolved as an extended strategy to expand the diversity of peptide nanoarchitectures. Here we systematically investigate the coassembly of diphenylalanine (FF) with each one of the 399 non-FF dipeptides by micro-second molecular dynamics simulations. Our simulations show that dipeptides, by coassembling with FF, display a greatly enhanced aggregation propensity and a significantly expanded structural diversity. Regular-shaped vesicles, single- or multi-cavity assemblies, and planar sheets are formed by coassembly of FF with different types of non-FF dipeptides, which are rarely observed in self-assemblies of non-FF dipeptides. Interaction analyses reveal that the formation of these varied structures is attributed to a delicate balance between aromatic stacking, hydrophobic, and electrostatic repulsion interactions. This study provides structural and mechanistic insights into the coassembly of FF and non-FF dipeptides, thus offering a possible way to achieve a controllable design of bionanomaterials through FF-involved dipeptide coassembly.


Assuntos
Dipeptídeos/química , Simulação de Dinâmica Molecular , Fenilalanina/análogos & derivados , Interações Hidrofóbicas e Hidrofílicas , Fenilalanina/química , Estrutura Secundária de Proteína
17.
Nanoscale ; 12(5): 3050-3057, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-31984970

RESUMO

As typical glucose oxidase nanozymes, gold nanoparticles (Au NPs) have attracted much attention due to their wide-ranging applications. Ligand caps, as the "cure-all solution" for NPs, not only play important roles in the size and shape control of Au NPs but also influence their catalytic activity and selectivity. A deep understanding of the catalytic mechanism and precise description of the important role of ligands can provide possible ways to design functional Au NPs. Here, with the specific example of Au(111) capped with chiral phenylalanine (Phe), the chiral selective oxidation mechanism of glucose and the important role of the ligands were studied via first-principles calculations. All results show that the dehydrogenation of glucose to form glucono delta-lactone (GDL) is favored on clean Au(111), while the subsequent hydrolysis of GDL is the rate-limiting step for glucose oxidation. The flat and nonchiral Au(111) surface shows negligible selectivity in relation to the oxidation of d- and l-glucose, while chiral Phe-Au(111) shows selective adsorption towards d- and l-glucose. l-Phe-capped Au(111) prefers to adsorb d-glucose, while d-Phe-capped Au(111) prefers to adsorb l-glucose. Considering the three steps in the capped ligand catalysis (adsorption, replacement and reaction), we propose that the ligands play key roles in selectively adsorbing reactants before the subsequent exchange and reaction steps.


Assuntos
Glucose/química , Ouro/química , Nanopartículas Metálicas/química , Fenilalanina/química , Catálise , Ligantes , Oxirredução
18.
J Phys Chem Lett ; 11(3): 891-899, 2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-31944766

RESUMO

Extreme-ultraviolet-induced charge migration in biorelevant molecules is a fundamental step in the complex path leading to photodamage. In this work we propose a simple interpretation of the charge migration recently observed in an attosecond pump-probe experiment on the amino acid tryptophan. We find that the decay of the prominent low-frequency spectral structure with increasing pump-probe delay is due to a quantum beating between two geometrically distinct, almost degenerate charge oscillations. Quantum beating is ubiquitous in these systems, and at least on the few-to-tens of femtosecond time scales, it may dominate over decoherence the line intensities of time-resolved spectra. We also address the experimentally observed phase shift in the charge oscillations of two different amino acids, tryptophan and phenylalanine. Our results indicate that a beyond mean-field treatment of the electron dynamics is necessary to reproduce the correct behavior.


Assuntos
Teoria da Densidade Funcional , Triptofano/química , Fenilalanina/química
19.
Eur J Med Chem ; 188: 112036, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31931341

RESUMO

Here, we describe the synthesis and biological characterization of 32 novel phenylalanine and leucine dipeptides modified on both the N and C termini by salicylic acid and aromatic or alicyclic amines, respectively. All compounds displayed antiproliferative activity in the tested cancer cell lines and eight of the compounds exhibited single digit micromolar GI50 values. Treated cells rapidly detached from surface of tissue culture dishes and we found that focal adhesion kinase (FAK), p130CAS and paxillin, which are important regulators of cell adhesion, were dephosphorylated at Y397, Y410 and Y118, respectively. The most potent compound reduced proliferation in the HCT-116 cell line in a dose-dependent manner, as shown by a decrease in 5-bromo-2'-deoxyuridine incorporation into DNA. Furthermore, this compound increased the levels of several apoptotic markers, including activated caspases, and increased site-specific poly-(ADP-ribose)polymerase (PARP) cleavage.


Assuntos
Antineoplásicos/farmacologia , Dipeptídeos/farmacologia , Leucina/farmacologia , Fenilalanina/farmacologia , Antineoplásicos/síntese química , Antineoplásicos/química , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Dipeptídeos/síntese química , Dipeptídeos/química , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Células HCT116 , Humanos , Leucina/síntese química , Leucina/química , Estrutura Molecular , Fenilalanina/síntese química , Fenilalanina/química , Relação Estrutura-Atividade , Células Tumorais Cultivadas
20.
J Agric Food Chem ; 68(5): 1397-1404, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31917559

RESUMO

Volatiles affect tea (Camellia sinensis) aroma quality and have roles in tea plant defense against stresses. Some volatiles defend against stresses through their toxicity, which might affect tea safety. Benzyl nitrile is a defense-related toxic volatile compound that accumulates in tea under stresses, but its formation mechanism in tea remains unknown. In this study, l-[2H8]phenylalanine feeding experiments and enzyme reactions showed that benzyl nitrile was generated from l-phenylalanine via phenylacetaldoxime in tea. CsCYP79D73 showed activity for converting l-phenylalanine into phenylacetaldoxime, while CsCYP71AT96s showed activity for converting phenylacetaldoxime into benzyl nitrile. Continuous wounding in the oolong tea process significantly enhanced the CsCYP79D73 expression level and phenylacetaldoxime and benzyl nitrile contents. Benzyl nitrile accumulation under continuous wounding stress was attributed to an increase in jasmonic acid, which activated CsCYP79D73 expression. This represents the first elucidation of the formation mechanism of benzyl nitrile in tea.


Assuntos
Camellia sinensis/metabolismo , Nitrilos/metabolismo , Fenilalanina/metabolismo , Camellia sinensis/química , Camellia sinensis/genética , Colesterol 7-alfa-Hidroxilase/genética , Colesterol 7-alfa-Hidroxilase/metabolismo , Ciclopentanos/metabolismo , Nitrilos/química , Oxilipinas/metabolismo , Fenilalanina/química , Folhas de Planta/genética , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estresse Fisiológico
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