Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 20.436
Filtrar
1.
Food Chem ; 370: 131271, 2022 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-34788952

RESUMO

5-Hydroxymethylfurfural (HMF) and acrylamide (AA) are neoformed food contaminants. In this study, the simultaneous inhibition of HMF and AA by histidine (His) were investigated. In the asparagine (Asn)/glucose (Glc) model system, the inhibition ratios of HMF and AA were in the range of 28-58% and 0-71% when 20 mmol/L His was added. In cookies, His also exhibited excellent inhibition effects on both HMF and AA. At the His concentration of 2% (w/w), the inhibition ratios of HMF and AA reached 90% and 65%. Additionally, the sensory quality of cookies was not affected significantly. Qualitative results suggested that His inhibited the formation of AA by the competitive reaction between His and Asn for Glc, as well as directly eliminated the formed HMF and AA via the carbonyl-amine reaction and the Michael addition, respectively. This study revealed that His could be applied for the inhibition of HMF and AA in heated food.


Assuntos
Acrilamida , Histidina , Asparagina , Furaldeído/análogos & derivados
2.
Anal Chim Acta ; 1187: 339162, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34753576

RESUMO

In this work, an auto-identify sensor was constructed for rapid and high-precision detection of L-histidine. The proposed strategy is based on the auto-identify algorithm and the aggregation of alkynyl and azide functionalized gold nanoparticles induced by the Cu+ catalyzed azides and alkynes cycloaddition (CuAAC) reaction. Specially, the color of scattering light spots for the aggregated gold nanoparticle (AuNPs) caused by CuAAC reaction was quite different from that of the monomers. However, L-histidine can bind to Cu2+ and inhibits the production of Cu+, hence preventing the aggregation of AuNPs. Therefore, there is a distinct change of color as the addition of L-histidine under dark-field microscopy. Then, L-histidine can be quantitatively detected by combining the color change with the Meanshift algorithm accurately and automatically. Such proposed method has been successfully applied for the detection of L-histidine in serum sample with satisfying result.


Assuntos
Ouro , Nanopartículas Metálicas , Algoritmos , Alcinos , Azidas , Catálise , Química Click , Cobre , Reação de Cicloadição , Histidina
3.
ACS Chem Neurosci ; 12(22): 4361-4366, 2021 11 17.
Artigo em Inglês | MEDLINE | ID: mdl-34735109

RESUMO

Research on misfolding of tau proteins will help to better understand the formation process of neurofibrillary tangles, a hallmark of Alzheimer's disease. Mutation and histidine tautomeric effects have been considered the two most important inherent factors for tau protein misfolding. In current research, replica-exchange molecular dynamics (REMD) were performed to characterize the structural properties of the key fragment R3 of tau protein under the collective effects of P332L mutation and histidine tautomerism. Simulation results suggest that though the content ß-sheet of P332L R3 εδ isomer is slightly lower than that of the WT P332L R3 fragment, the total stable secondary structures including ß-sheet and helix of P332L R3 isomers are generally more prevalent than those of wild type R3, which may be the reason that P332L R3 has a higher aggregation tendency. Further analysis showed that the hydrogen bond networks are affected by the mutation and histidine tautomerism. Furthermore, the interactions between N-terminus and C-terminus play a crucial role in ß-hairpin formation in all isomers. The current study will contribute to revealing the collective effects of P332L and histidine tautomerism on the misfolding of tau proteins.


Assuntos
Doença de Alzheimer , Proteínas tau , Doença de Alzheimer/genética , Histidina/genética , Humanos , Mutação/genética , Emaranhados Neurofibrilares/metabolismo , Conformação Proteica em Folha beta , Proteínas tau/genética , Proteínas tau/metabolismo
4.
Anal Chem ; 93(45): 14985-14995, 2021 11 16.
Artigo em Inglês | MEDLINE | ID: mdl-34735131

RESUMO

Identifying the targets of a drug is critical to understand the mechanism of action and predicts possible side effects. The conventional approach is capturing interacting proteins by affinity purification. However, it requires drugs to be immobilized to a solid support or derivatized with chemical moieties used for pulling down interacting proteins. Such covalent modifications to drugs may mask a critical recognition site for or alter the binding affinity to their targets. To overcome the drawback, several methods that do not require covalent modifications to drugs have been developed. These methods identify targets by detecting proteins whose thermodynamic stability is enhanced in the presence of drugs. Although the utility of these methods has been demonstrated, the difficulty in identifying low abundant targets is the common problem of these methods. We have developed a new target identification method that increases the likelihood of identifying low abundant targets. The method uses histidine-hydrogen deuterium exchange (His-HDX) as a readout technique to probe the changes in protein stability induced by drugs. The workflow involves incubating cell lysates in various concentrations of a protein denaturant in the presence and absence of a drug in D2O followed by digestion of the proteins, enrichment of His-containing peptides, and analysis of the enriched His-peptides by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The developed method was successfully applied to identify the interaction between endogenously expressed MAPK14 and its inhibitor in HEK293 cell lysates. The implementation of selective enrichment of histidine-containing peptides in the workflow was a key that enabled identifying the MAPK14-inhibitor interaction.


Assuntos
Medição da Troca de Deutério , Histidina , Cromatografia Líquida , Deutério , Interações Medicamentosas , Células HEK293 , Humanos , Hidrogênio , Espectrometria de Massas em Tandem
5.
Int J Mol Sci ; 22(19)2021 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-34639146

RESUMO

The phosphoenolpyruvate-dependent phosphotransferase system (PTS) modulates the preferential use of sugars in bacteria. The first proteins in the cascade are common to all organisms (EI and HPr). The active site of HPr involves a histidine (His15) located immediately before the beginning of the first α-helix. The regulator of sigma D (Rsd) protein also binds to HPr. The region of HPr comprising residues Gly9-Ala30 (HPr9-30), involving the first α-helix (Ala16-Thr27) and the preceding active site loop, binds to both the N-terminal region of EI and intact Rsd. HPr9-30 is mainly disordered. We attempted to improve the affinity of HPr9-30 to both proteins by mutating its sequence to increase its helicity. We designed peptides that led to a marginally larger population in solution of the helical structure of HPr9-30. Molecular simulations also suggested a modest increment in the helical population of mutants, when compared to the wild-type. The mutants, however, were bound with a less favorable affinity than the wild-type to both the N-terminal of EI (EIN) or Rsd, as tested by isothermal titration calorimetry and fluorescence. Furthermore, mutants showed lower antibacterial properties against Staphylococcus aureus than the wild-type peptide. Therefore, we concluded that in HPr, a compromise between binding to its partners and residual structure at the active site must exist to carry out its function.


Assuntos
Antibacterianos/farmacologia , Proteínas de Bactérias/metabolismo , Histidina/metabolismo , Mutação , Fragmentos de Peptídeos/farmacologia , Sistema Fosfotransferase de Açúcar do Fosfoenolpiruvato/metabolismo , Staphylococcus aureus/efeitos dos fármacos , Antibacterianos/química , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Sítios de Ligação , Domínio Catalítico , Histidina/química , Fragmentos de Peptídeos/química , Sistema Fosfotransferase de Açúcar do Fosfoenolpiruvato/química , Sistema Fosfotransferase de Açúcar do Fosfoenolpiruvato/genética , Staphylococcus aureus/metabolismo
6.
Front Cell Infect Microbiol ; 11: 742681, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34621693

RESUMO

Early diagnosis and treatment are fundamental to the control and elimination of malaria. In many endemic areas, routine diagnosis is primarily performed microscopically, although rapid diagnostic tests (RDTs) provide a useful point-of-care tool. Most of the commercially available RDTs detect histidine-rich protein 2 (HRP2) of Plasmodium falciparum in the blood of infected individuals. Nonetheless, parasite isolates lacking the pfhrp2 gene are relatively frequent in some endemic regions, thereby hampering the diagnosis of malaria using HRP2-based RDTs. To track the efficacy of RDTs in areas of the Brazilian Amazon, we assessed pfhrp2 deletions in 132 P. falciparum samples collected from four malaria-endemic states in Brazil. Our findings show low to moderate levels of pfhrp2 deletion in different regions of the Brazilian Amazon. Overall, during the period covered by this study (2002-2020), we found that 10% of the P. falciparum isolates were characterized by a pfhrp2 deletion. Notably, however, the presence of pfhrp2-negative isolates has not been translated into a reduction in RDT efficacy, which in part may be explained by the presence of polyclonal infections. A further important finding was the discrepancy in the proportion of pfhrp2 deletions detected using two assessed protocols (conventional PCR versus nested PCR), which reinforces the need to perform a carefully planned laboratory workflow to assess gene deletion. This is the first study to perform a comprehensive analysis of PfHRP2 sequence diversity in Brazilian isolates of P. falciparum. We identified 10 PfHRP2 sequence patterns, which were found to be exclusive of each of the assessed regions. Despite the small number of PfHRP2 sequences available from South America, we found that the PfHRP2 sequences identified in Brazil and neighboring French Guiana show similar sequence patterns. Our findings highlight the importance of continuously monitoring the occurrence and spread of parasites with pfrhp2 deletions, while also taking into account the limitations of PCR-based testing methods associated with accuracy and the complexity of infections.


Assuntos
Malária Falciparum , Plasmodium falciparum , Antígenos de Protozoários/genética , Brasil , Testes Diagnósticos de Rotina , Deleção de Genes , Histidina , Humanos , Malária Falciparum/diagnóstico , Plasmodium falciparum/genética , Proteínas de Protozoários/genética
7.
Hum Genet ; 140(12): 1709-1731, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34652576

RESUMO

Microtubules are formed from heterodimers of alpha- and beta-tubulin, each of which has multiple isoforms encoded by separate genes. Pathogenic missense variants in multiple different tubulin isoforms cause brain malformations. Missense mutations in TUBB3, which encodes the neuron-specific beta-tubulin isotype, can cause congenital fibrosis of the extraocular muscles type 3 (CFEOM3) and/or malformations of cortical development, with distinct genotype-phenotype correlations. Here, we report fourteen individuals from thirteen unrelated families, each of whom harbors the identical NM_006086.4 (TUBB3):c.785G>A (p.Arg262His) variant resulting in a phenotype we refer to as the TUBB3 R262H syndrome. The affected individuals present at birth with ptosis, ophthalmoplegia, exotropia, facial weakness, facial dysmorphisms, and, in most cases, distal congenital joint contractures, and subsequently develop intellectual disabilities, gait disorders with proximal joint contractures, Kallmann syndrome (hypogonadotropic hypogonadism and anosmia), and a progressive peripheral neuropathy during the first decade of life. Subsets may also have vocal cord paralysis, auditory dysfunction, cyclic vomiting, and/or tachycardia at rest. All fourteen subjects share a recognizable set of brain malformations, including hypoplasia of the corpus callosum and anterior commissure, basal ganglia malformations, absent olfactory bulbs and sulci, and subtle cerebellar malformations. While similar, individuals with the TUBB3 R262H syndrome can be distinguished from individuals with the TUBB3 E410K syndrome by the presence of congenital and acquired joint contractures, an earlier onset peripheral neuropathy, impaired gait, and basal ganglia malformations.


Assuntos
Paralisia Facial/genética , Fibrose/genética , Mutação , Oftalmoplegia/genética , Doenças do Sistema Nervoso Periférico/genética , Tubulina (Proteína)/genética , Anormalidades Múltiplas/genética , Adolescente , Adulto , Substituição de Aminoácidos , Arginina , Criança , Pré-Escolar , Paralisia Facial/diagnóstico , Paralisia Facial/fisiopatologia , Feminino , Fibrose/diagnóstico , Fibrose/fisiopatologia , Histidina , Humanos , Lactente , Masculino , Oftalmoplegia/diagnóstico , Oftalmoplegia/fisiopatologia , Doenças do Sistema Nervoso Periférico/diagnóstico , Doenças do Sistema Nervoso Periférico/fisiopatologia , Síndrome , Adulto Jovem
8.
Proc Natl Acad Sci U S A ; 118(39)2021 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-34556577

RESUMO

Proteins achieve efficient energy storage and conversion through electron transfer along a series of redox cofactors. Multiheme cytochromes are notable examples. These proteins transfer electrons over distance scales of several nanometers to >10 µm and in so doing they couple cellular metabolism with extracellular redox partners including electrodes. Here, we report pump-probe spectroscopy that provides a direct measure of the intrinsic rates of heme-heme electron transfer in this fascinating class of proteins. Our study took advantage of a spectrally unique His/Met-ligated heme introduced at a defined site within the decaheme extracellular MtrC protein of Shewanella oneidensis We observed rates of heme-to-heme electron transfer on the order of 109 s-1 (3.7 to 4.3 Å edge-to-edge distance), in good agreement with predictions based on density functional and molecular dynamics calculations. These rates are among the highest reported for ground-state electron transfer in biology. Yet, some fall 2 to 3 orders of magnitude below the Moser-Dutton ruler because electron transfer at these short distances is through space and therefore associated with a higher tunneling barrier than the through-protein tunneling scenario that is usual at longer distances. Moreover, we show that the His/Met-ligated heme creates an electron sink that stabilizes the charge separated state on the 100-µs time scale. This feature could be exploited in future designs of multiheme cytochromes as components of versatile photosynthetic biohybrid assemblies.


Assuntos
Grupo dos Citocromos c/metabolismo , Citocromos/metabolismo , Elétrons , Heme/metabolismo , Histidina/metabolismo , Metionina/metabolismo , Shewanella/metabolismo , Grupo dos Citocromos c/química , Citocromos/química , Transporte de Elétrons , Heme/química , Histidina/química , Metionina/química , Simulação de Dinâmica Molecular , Nanofios , Oxirredução
9.
DNA Cell Biol ; 40(10): 1325-1337, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34582699

RESUMO

Psoriasis is a chronic inflammatory skin disease characterized by massive keratinocyte proliferation and immune cell infiltration into the epidermis. However, the specific mechanisms underlying the development of psoriasis remain unclear. Untargeted metabolomics and transcriptomics have been used separately to profile biomarkers and risk genes in the serum of psoriasis patients. However, the integration of metabolomics and transcriptomics to identify dysregulated metabolites and genes in the psoriatic skin is lacking. In this study, we performed an untargeted metabolomics analysis of imiquimod (IMQ)-induced psoriasis-like mice and healthy controls, and found that levels of a total of 4,188 metabolites differed in IMQ-induced psoriasis-like mice compared with those in control mice. Metabolomic data analysis using MetaboAnalyst showed that the metabolic pathways of primary metabolites, such as folate biosynthesis and galactose metabolism, were significantly altered in the skin of mice after treatment with IMQ. Furthermore, IMQ treatment also significantly altered metabolic pathways of secondary metabolites, including histidine metabolism, in mouse skin tissues. The metabolomic results were verified by transcriptomics analysis. RNA-seq results showed that histamine decarboxylase (HDC) mRNA levels were significantly upregulated after IMQ treatment. Targeted inhibition of histamine biosynthesis process using HDC-specific inhibitor, pinocembrin (PINO), significantly alleviated epidermal thickness, downregulated the expression of interleukin (IL)-17A and IL-23, and inhibited the infiltration of immune cells during IMQ-induced psoriasis-like skin inflammation. In conclusion, our study offers a validated and comprehensive understanding of metabolism during the development of psoriasis and demonstrated that PINO could protect against IMQ-induced psoriasis-like skin inflammation.


Assuntos
Histidina/metabolismo , Metaboloma , Psoríase/metabolismo , Transcriptoma , Animais , Feminino , Imiquimode/toxicidade , Camundongos , Camundongos Endogâmicos C57BL , Psoríase/etiologia , Psoríase/genética
11.
Poult Sci ; 100(11): 101393, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34530228

RESUMO

The high growth rates of modern broiler breeds increased the risk for novel breast muscle myopathies as serious quality issue, relevant for the industry. In affected muscles, a depletion of the dipeptides carnosine and anserine was reported. Therefore, this study was performed to test whether a supplementation of the precursors histidine and ß-alanine, alone or in combination can increase the dipeptide content in the breast muscle and improve meat quality. Ross 308 broiler chickens were supplemented with 3 different histidine:lysine ratios (0.44, 0.54, 0.64) of standardized ileal digestible amino acids (SID) combined with 0 or 0.5% ß-alanine in total. The birds' performance was recorded at different ages: birds were slaughtered in 2 batches after 33 and 53 d of life. Meat quality was tested at different time points after slaughter on breast fillets stored aerobically. The concentration of the dipeptides and amino acids in blood plasma and muscle tissue was tested postmortem at 35 and 54 d. All performance and meat quality data, as well as peptide and amino acid concentrations, of the 2 × 2 × 3 randomized block design were analyzed separately for the influence of both supplements and for slaughter age. Moreover, the influence of storage time was analyzed separately for meat quality parameters. At both slaughter ages, lesser feed intake (P ≤ 0.005) and breast yield (P ≤ 0.05) were observed in the birds receiving ß-alanine. A greater SID histidine:lysine ratio increased the carnosine concentrations in blood plasma (P < 0.001) and in skeletal muscle (P < 0.001), whereas ß-alanine increased carnosine in plasma at 35 d only (P = 0.004). Anserine was increased in plasma and muscle of older birds (P = 0.003), whereas carnosine was reduced in muscle tissue (P < 0.001). The main impact on meat quality parameters was seen for the age of the birds and storage time of the fillets. In conclusion, the supplementation of histidine increased carnosine in breast muscle but both supplements showed only minor effects on meat quality.


Assuntos
Carnosina , Ração Animal/análise , Animais , Galinhas , Histidina , Carne/análise , Músculos Peitorais , beta-Alanina
12.
Nat Commun ; 12(1): 4845, 2021 08 11.
Artigo em Inglês | MEDLINE | ID: mdl-34381036

RESUMO

The human gut microbiota is increasingly recognized as an important factor in modulating innate and adaptive immunity through release of ligands and metabolites that translocate into circulation. Urbanizing African populations harbor large intestinal diversity due to a range of lifestyles, providing the necessary variation to gauge immunomodulatory factors. Here, we uncover a gradient of intestinal microbial compositions from rural through urban Tanzanian, towards European samples, manifested both in relative abundance and genomic variation observed in stool metagenomics. The rural population shows increased Bacteroidetes, led by Prevotella copri, but also presence of fungi. Measured ex vivo cytokine responses were significantly associated with 34 immunomodulatory microbes, which have a larger impact on circulating metabolites than non-significant microbes. Pathway effects on cytokines, notably TNF-α and IFN-γ, differential metabolome analysis and enzyme copy number enrichment converge on histidine and arginine metabolism as potential immunomodulatory pathways mediated by Bifidobacterium longum and Akkermansia muciniphila.


Assuntos
Citocinas/imunologia , Microbioma Gastrointestinal/fisiologia , População Rural , População Urbana , Adulto , Arginina/metabolismo , Bactérias/imunologia , Bactérias/isolamento & purificação , Bactérias/metabolismo , Dieta , Feminino , Microbioma Gastrointestinal/imunologia , Histidina/metabolismo , Humanos , Imunomodulação , Masculino , Redes e Vias Metabólicas , Metaboloma/imunologia , Fatores Socioeconômicos , Tanzânia , Urbanização
13.
Biomacromolecules ; 22(9): 3941-3949, 2021 09 13.
Artigo em Inglês | MEDLINE | ID: mdl-34347452

RESUMO

A novel dual pH/thermoresponsive amphiphilic poly(histidine methacrylamide)-block-hydroxyl-terminated polybutadiene-block-poly(histidine methacrylamide) (PHisMAM-b-PB-b-PHisMAM) triblock copolymer biohybrid, composed of hydrophobic PB and ampholytic PHisMAM segments, is developed via direct switching from living anionic polymerization to recyclable nanoparticle catalyst-mediated reversible-deactivation radical polymerization (RDRP). The transformation involved in situ postpolymerization modification of living polybutadiene-based carbanionic species, end-capped with ethylene oxide, into dihydroxyl-terminated polybutadiene and a subsequent reaction with 2-bromo-2-methylpropionyl bromide resulting in a telechelic ATRP macroinitiator (Br-PB-Br). Br-PB-Br was used to mediate RDRP of an l-histidine-derived monomer, HisMAM, yielding a series of PHisMAM-b-PB-b-PHisMAM triblock copolymers. The copolymer's stimuli response was assessed against pH and temperature changes. The copolymer is capable of switching among its zwitterionic, anionic, and cationic forms and exhibited unique antifouling properties in its zwitterionic form. These novel triblock copolymers are expected to be show promising potential in biomedical applications.


Assuntos
Incrustação Biológica , Histidina , Incrustação Biológica/prevenção & controle , Micelas , Polimerização , Polímeros
14.
Chemistry ; 27(53): 13330-13336, 2021 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-34357653

RESUMO

The N-arylation of the side chain of histidine by using triarylbismuthines is reported. The reaction is promoted by copper(II) acetate in dichloromethane at 40 °C under oxygen in the presence of diisopropylethylamine and 1,10-phenanthroline and allows the transfer of aryl groups with substituents at any position of the aromatic ring. The reaction shows excellent functional group tolerance and is applicable to dipeptides where the histidine is located at the N terminus. A histidine-guided backbone N-H arylation was observed in dipeptides where the histidine occupies the C terminus.


Assuntos
Cobre , Histidina , Catálise , Imidazóis , Indicadores e Reagentes
15.
Cells ; 10(8)2021 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-34440612

RESUMO

Assessment of humoral immunity to SARS-CoV-2 and other infectious agents is typically restricted to detecting antigen-specific antibodies in the serum. Rarely does immune monitoring entail assessment of the memory B-cell compartment itself, although it is these cells that engage in secondary antibody responses capable of mediating immune protection when pre-existing antibodies fail to prevent re-infection. There are few techniques that are capable of detecting rare antigen-specific B cells while also providing information regarding their relative abundance, class/subclass usage and functional affinity. In theory, the ELISPOT/FluoroSpot (collectively ImmunoSpot) assay platform is ideally suited for antigen-specific B-cell assessments since it provides this information at single-cell resolution for individual antibody-secreting cells (ASC). Here, we tested the hypothesis that antigen-coating efficiency could be universally improved across a diverse set of viral antigens if the standard direct (non-specific, low affinity) antigen absorption to the membrane was substituted by high-affinity capture. Specifically, we report an enhancement in assay sensitivity and a reduction in required protein concentrations through the capture of recombinant proteins via their encoded hexahistidine (6XHis) affinity tag. Affinity tag antigen coating enabled detection of SARS-CoV-2 Spike receptor binding domain (RBD)-reactive ASC, and also significantly improved assay performance using additional control antigens. Collectively, establishment of a universal antigen-coating approach streamlines characterization of the memory B-cell compartment after SARS-CoV-2 infection or COVID-19 vaccinations, and facilitates high-throughput immune-monitoring efforts of large donor cohorts in general.


Assuntos
Antígenos Virais/análise , Linfócitos B/imunologia , ELISPOT/métodos , Memória Imunológica , SARS-CoV-2/imunologia , Proteínas Virais/imunologia , Animais , COVID-19 , Histidina , Humanos , Camundongos , Oligopeptídeos , SARS-CoV-2/metabolismo
16.
ACS Chem Neurosci ; 12(17): 3203-3213, 2021 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-34382391

RESUMO

The aggregation and structural conversion of normal prion peptide (PrPC) into the pathogenic scrapie form (PrPSc), which can act as a seed to enhance prion amyloid fiber formation, is believed to be a crucial event in prionopathies. Previous research suggests that the prion monomer may play an important role in oligomer generation during disease pathogenesis. In the present study, extensive replica-exchange molecular dynamics (REMD) simulations were conducted to explore the conformational characteristics of the huPrP (125-160) monomer under the histidine tautomerism effect. Investigating the structural characteristics and fibrilization process is challenging because two histidine tautomers [Nε2-H (ε) and Nδ1-H (δ)] can occur in the open neutral state. Molecular dynamics (MD) simulation outcomes have shown that the toxic εδ and δδ isomer (containing several and broader local minima) had the highest α-helix structures, with contents of 21.11% and 21.01%, respectively, and may have a strong influence on the organizational behavior of a monomeric prion. The amino acids aspartate 20 (D20)-asparagine 29 (N29) and isoleucine 15 (I15)-histidine 16 (H16), D20-arginine 27 (R27) as well as N29 formed α-helix with the highest probabilities in the δδ and εδ isomer, accordingly. On the basis of our findings, we propose the histidine tautomerization hypothesis as a new prion accumulation mechanism, which may exist to induce the formation of prion accumulates. Overall, our tautomerism hypothesis constitutes a promising perspective for enhancing understanding of prion disease pathobiology and may help in the design of a good inhibitor.


Assuntos
Príons , Scrapie , Amiloide , Animais , Histidina , Simulação de Dinâmica Molecular , Ovinos
17.
Phys Chem Chem Phys ; 23(31): 16698-16706, 2021 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-34338250

RESUMO

The kinetics of electron transfer (ET) from tyrosine (Tyr) to short-lived histidine (His) radicals in peptides of different structures was monitored using time-resolved chemically induced dynamic nuclear polarization (CIDNP) to follow the reduction of the His radicals using NMR detection of the diamagnetic hyperpolarized reaction products. In aqueous solution over a wide pH range, His radicals were generated in situ in the photo-induced reaction with the photosensitizer, 3,3',4,4'-tetracarboxy benzophenone. Model simulations of the CIDNP kinetics provided pH-dependent rate constants of intra- and intermolecular ET, and the pH dependencies of the reaction under study were interpreted in terms of protonation states of the reactants and the product, His with either protonated or neutral imidazole. In some cases, an increase of pKa of imidazole in the presence of the short-lived radical center at a nearby Tyr residue was revealed. Interpretation of the obtained pH dependencies made is possible to quantify the degree of paramagnetic shift of the acidity constant of the imidazole of the His residue in the peptides with a Tyr residue in its paramagnetic state, and to correlate this degree with the intramolecular ET rate constant - a higher intramolecular ET rate constant corresponded to a greater acidity constant shift.


Assuntos
Histidina/química , Peptídeos/química , Tirosina/química , Transporte de Elétrons , Concentração de Íons de Hidrogênio , Cinética , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Oxirredução
18.
J Clin Exp Hematop ; 61(3): 145-151, 2021 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-34334531

RESUMO

We established an IL-2 and IL-4 (IL2/4) - dependent adult T-cell leukemia/lymphoma (ATLL) cell line (YG-PLL) by adding poly-L-lysine (PLL) to the culture medium. YG-PLL originates from lymphoma cells and contains a defective HTLV-I proviral genome. Although YG-PLL cannot survive without IL-2/4, the follicular dendritic cell (FDC)-like cell line HK expressing OX40-ligand gene (OX40L+HK) inhibited their death in the presence of soluble neutral polymers. After the prevention of cell death, YG-PLL proliferated on OX40L+HK without IL2/4 in the presence of two kinds of positively or negatively charged polymers. In particular, dermatan sulfate and poly-L-histidine supported growth for more than 4 months. Therefore, the original lymphoma cells proliferated transiently in the presence of IL2/4, and their growth arrest was inhibited by the addition of PLL. Furthermore, YG-PLL lost IL2/4 dependency by the following 3-step procedure: preculture with IL2/4 and neutral polymers, 3-day culture with neutral polymer on OX40L+HK to inhibit cell death, and co-culture with OX40L+HK in the presence of the positively and negatively charged polymers. The extracellular environment made by soluble polymers plays a role in the growth of ATLL in vitro.


Assuntos
Linhagem Celular Tumoral , Dermatan Sulfato/farmacologia , Histidina/farmacologia , Interleucina-2/metabolismo , Interleucina-4/metabolismo , Leucemia-Linfoma de Células T do Adulto/etiologia , Leucemia-Linfoma de Células T do Adulto/metabolismo , Ligante OX40/metabolismo , Células Dendríticas Foliculares/imunologia , Células Dendríticas Foliculares/metabolismo , Expressão Gênica , Humanos , Leucemia-Linfoma de Células T do Adulto/patologia , Ligante OX40/genética
19.
Appl Environ Microbiol ; 87(20): e0133521, 2021 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-34347519

RESUMO

ß-Hydroxy-α-amino acids are useful compounds for pharmaceutical development. Enzymatic synthesis of ß-hydroxy-α-amino acids has attracted considerable interest as a selective, sustainable, and environmentally benign process. In this study, we identified a novel amino acid hydroxylase, AEP14369, from Sulfobacillus thermotolerans Y0017, which is included in a previously constructed CAS-like superfamily protein library, to widen the variety of amino acid hydroxylases. The detailed structures determined by nuclear magnetic resonance and X-ray crystallography analysis of the enzymatically produced compounds revealed that AEP14369 catalyzed threo-ß-selective hydroxylation of l-His and l-Gln in a 2-oxoglutarate-dependent manner. Furthermore, the production of l-threo-ß-hydroxy-His and l-threo-ß-hydroxy-Gln was achieved using Escherichia coli expressing the gene encoding AEP14369 as a whole-cell biocatalyst. Under optimized reaction conditions, 137 mM (23.4 g liter-1) l-threo-ß-hydroxy-His and 150 mM l-threo-ß-hydroxy-Gln (24.3 g liter-1) were obtained, indicating that the enzyme is applicable for preparative-scale production. AEP14369, an l-His/l-Gln threo-ß-hydroxylase, increases the availability of 2-oxoglutarate-dependent hydroxylase and opens the way for the practical production of ß-hydroxy-α-amino acids in the future. The amino acids produced in this study would also contribute to the structural diversification of pharmaceuticals that affect important bioactivities. IMPORTANCE Owing to an increasing concern for sustainability, enzymatic approaches for producing industrially useful compounds have attracted considerable attention as a powerful complement to chemical synthesis for environment-friendly synthesis. In this study, we developed a bioproduction method for ß-hydroxy-α-amino acid synthesis using a newly discovered enzyme. AEP14369 from the moderate thermophilic bacterium Sulfobacillus thermotolerans Y0017 catalyzed the hydroxylation of l-His and l-Gln in a regioselective and stereoselective fashion. Furthermore, we biotechnologically synthesized both l-threo-ß-hydroxy-His and l-threo-ß-hydroxy-Gln with a titer of over 20 g liter-1 through whole-cell bioconversion using recombinant Escherichia coli cells. As ß-hydroxy-α-amino acids are important compounds for pharmaceutical development, this achievement would facilitate future sustainable and economical industrial applications.


Assuntos
Proteínas de Bactérias/metabolismo , Clostridiales/enzimologia , Glicina/metabolismo , Histidina/metabolismo , Ácidos Cetoglutáricos/metabolismo , Oxigenases de Função Mista/metabolismo , Proteínas de Bactérias/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Glicina/análogos & derivados , Histidina/análogos & derivados , Hidroxilação , Oxigenases de Função Mista/genética
20.
Chem Asian J ; 16(17): 2453-2462, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34231327

RESUMO

Early oligomerization of human islet amyloid polypeptide (hIAPP), which is accountable for ß-cell death, has been implicated in the progression of type 2 diabetes mellitus. Some researches have shown the connection between hIAPP and Alzheimer's disease as well. However, the mechanism of peptide accumulation and associated cytotoxicity remains unclear. Due to the unique properties and significant role of histidine in protein sequences, here for the first time, the tautomeric effect of histidine at the early stages of amylin misfolding was investigated via molecular dynamics simulations. Considering Tau and Pi tautomeric forms of histidine (Tau and Pi tautomers are denoted as ϵ and δ, respectively), simulations were performed on two possible isomers of amylin. Our analysis revealed a higher probability of transient α-helix generation in the δ isomer in monomeric form. In dimeric forms, the δδ and δϵ conformations showed an elevated amount of α-helix and lower coil in comparison to the ϵϵ dimer. Due to the significant role of α-helix in membrane disruption and transition to ß-sheet structure, these results may imply a noticeable contribution of the δ isomer and the δδ and δϵ dimers rather than ϵ and ϵϵ conformations in the early stages of diabetes initiation. Our results may aid in elucidating the hIAPP self-association process in the etiology of amyloidosis.


Assuntos
Histidina/química , Polipeptídeo Amiloide das Ilhotas Pancreáticas/metabolismo , Multimerização Proteica , Humanos , Ligação de Hidrogênio , Polipeptídeo Amiloide das Ilhotas Pancreáticas/química , Isomerismo , Simulação de Dinâmica Molecular , Análise de Componente Principal , Conformação Proteica em alfa-Hélice
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...