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1.
J Liposome Res ; : 1-12, 2024 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-39363444

RESUMO

Vesicular nanocarriers like niosomes and liposomes are widely researched for controlled drug delivery systems, with niosomes emerging as promising alternatives due to their higher stability and ease of manufacturing. This study aimed to develop and characterize a niosomal formulation for the encapsulation and sustained release of temozolomide (TMZ), a model lipophilic drug, and to compare the stability of niosomes and liposomes, with a particular focus on the behavior of their lipid bilayers. Niosomes were prepared using the thin-film hydration method, composed of Span 60 (Sorbitan monostearate), cholesterol, and soy lecithin in varying molar ratios. The study investigated critical properties such as drug loading capacity, release kinetics, and resistance to enzymatic degradation. The optimized formulation was analyzed for drug entrapment efficiency and stability against phospholipase A2 (PLA2) degradation. The optimized niosomal formulation, with a 4:2:1 molar ratio of Span 60: cholesterol, achieved a high TMZ entrapment efficiency of 73.23 ± 1.02% and demonstrated sustained drug release over 24 hours. In comparison, liposomes released their TMZ payload within 4 hours upon exposure to PLA2, while the niosomes maintained their release profile, indicating superior stability. Spectroscopic and thermal analysis confirmed successful drug encapsulation with no component incompatibilities.

2.
J Biol Chem ; 296: 100657, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33857478

RESUMO

The integrin αvß6 is an antigen expressed at low levels in healthy tissue but upregulated during tumorigenesis, which makes it a promising target for cancer imaging and therapy. A20FMDV2 is a 20-mer peptide derived from the foot-and-mouth disease virus that exhibits nanomolar and selective affinity for αvß6 versus other integrins. Despite this selectivity, A20FMDV2 has had limited success in imaging and treating αvß6+ tumors in vivo because of its poor serum stability. Here, we explore the cyclization and modification of the A20FMDV2 peptide to improve its serum stability without sacrificing its affinity and specificity for αvß6. Using cysteine amino acid substitutions and cyclization by perfluoroarylation with decafluorobiphenyl, we synthesized six cyclized A20FMDV2 variants and discovered that two retained binding to αvß6 with modestly improved serum stability. Further d-amino acid substitutions and C-terminal sequence optimization outside the cyclized region greatly prolonged peptide serum stability without reducing binding affinity. While the cyclized A20FMDV2 variants exhibited increased nonspecific integrin binding compared with the original peptide, additional modifications with the non-natural amino acids citrulline, hydroxyproline, and d-alanine were found to restore binding specificity, with some modifications leading to greater αvß6 integrin selectivity than the original A20FMDV2 peptide. The peptide modifications detailed herein greatly improve the potential of utilizing A20FMDV2 to target αvß6 in vivo, expanding opportunities for cancer targeting and therapy.


Assuntos
Antígenos de Neoplasias/metabolismo , Integrinas/metabolismo , Neoplasias/metabolismo , Fragmentos de Peptídeos/metabolismo , Compostos Radiofarmacêuticos/metabolismo , Soro/química , Proteínas do Envelope Viral/metabolismo , Ciclização , Vírus da Febre Aftosa/metabolismo , Humanos , Células K562 , Neoplasias/diagnóstico por imagem , Neoplasias/patologia
3.
Protein Expr Purif ; 190: 106009, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34742914

RESUMO

The enzymatic conversion of lignocellulosic biomass to fermentable sugars is determined by the enzymatic activity of cellulases; consequently, improving enzymatic activity has attracted great interest in the scientific community. Cocktails of commercial cellulase often have low ß-glucosidase content, leading to the accumulation of cellobiose. This accumulation inhibits the activity of the cellulolytic complex and can be used to determine the enzymatic efficiency of commercial cellulase cocktails. Here, a novel codon optimized ß-glucosidase gene (B-glusy) from Trichoderma reesei QM6a was cloned and expressed in three strains of Escherichia coli (E. coli). The synthetic sequence containing an open reading frame (ORF) of 1491 bp was used to encode a polypeptide of 497 amino acid residues. The ß-glucosidase recombinant protein that was expressed (57 kDa of molecular weight) was purified by Ni agarose affinity chromatography and visualized by SDS-PAGE. The recombinant protein was better expressed in E. coli BL21 (DE3), and its enzymatic activity was higher at neutral pH and 30 °C (22.4 U/mg). Subsequently, the ß-glucosidase was immobilized using magnetite nano-support, after which it maintained >65% of its enzymatic activity from pH 6 to 10, and was more stable than the free enzyme above 40 °C. The maximum immobilization yield had enzyme activity of 97.2%. In conclusion, ß-glucosidase is efficiently expressed in the microbial strain E. coli BL21 (DE3) grown in a simplified culture medium.


Assuntos
Enzimas Imobilizadas , Escherichia coli , Proteínas Fúngicas , Expressão Gênica , Hypocreales/genética , Nanopartículas de Magnetita/química , beta-Glucosidase , Estabilidade Enzimática , Enzimas Imobilizadas/biossíntese , Enzimas Imobilizadas/química , Enzimas Imobilizadas/genética , Enzimas Imobilizadas/isolamento & purificação , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas Fúngicas/biossíntese , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Proteínas Fúngicas/isolamento & purificação , Hypocreales/enzimologia , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , beta-Glucosidase/biossíntese , beta-Glucosidase/química , beta-Glucosidase/genética , beta-Glucosidase/isolamento & purificação
4.
Chem Pharm Bull (Tokyo) ; 70(10): 699-706, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36184452

RESUMO

Chemically modified nucleic acids are essential for the therapeutic application of oligonucleotides. In this study, 6'-C-spiro-thymidine exhibiting a fixed torsion angle γ was designed, synthesized, and incorporated into oligonucleotides. The conformational analysis of the 6'-C-spiro-thymidine monomer revealed that its torsion angle γ was in the +synclinal range (approx. 60°), which is similar to that in a natural RNA duplex, as expected. On the other hand, the sugar conformation of the RNA duplex is known to be predominantly an N-type, whereas that of the synthesized monomer was an S-type. The results of the UV melting analysis demonstrated that the duplex-forming ability of 6'-C-spiro-thymidine was inferior to that of natural DNA. Contrarily, 6'-C-spiro-thymidine could enhance the stability of oligonucleotides toward nucleases. Particularly, the incorporation of 6'-C-spiro-thymidine on the 3'-ends of the oligonucleotides significantly increased the nuclease resistance of the oligonucleotides.


Assuntos
Ácidos Nucleicos , Oligonucleotídeos , Alcanos , DNA/química , Oligonucleotídeos/química , RNA , Esqueleto , Compostos de Espiro , Açúcares , Timidina/química
5.
Compr Rev Food Sci Food Saf ; 21(6): 4716-4737, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36181483

RESUMO

Pineapple juice is preferred by consumers for its unique aroma and flavor that come from a set of amino acids, amines, phenolic compounds, and furanone. The juice is susceptible to spoilage, and a common practice is to pasteurize it at 70-95°C for 0.5-5 min. However, the characteristic flavors and phytochemicals are negatively influenced by the intense time-temperature treatment. To retain the thermosensitive compounds in the juice, some nonthermal technologies such as high-pressure processing, pulsed electric field, pulsed light, ultrasound, and ultraviolet treatments have been explored. These techniques ensured microbial safety (5-log reduction in E. coli, S. Typhimurium, or S. cerevisiae) while preserving a maximum ascorbic acid (84-99%) in the juice. The shelf life of these nonthermally treated juice varied between 14 days (UV treated at 7.5 mJ/cm2 ) and 6 months (clarified through microfiltration). Moreover, the inactivation of spoilage enzyme in the juice required a higher intensity. The present review discusses the potential of several nonthermal techniques employed for the pasteurization of pineapple juice. The pasteurization ability of the combined hurdle between mild thermal and nonthermal processing is also presented. The review also summarizes the target for pasteurization, the plan to design a nonthermal processing intensity, and the consumer perspective toward nonthermally treated pineapple juice. The techniques are compared on the common ground like safety, stability, and quality of the juice. This will help readers to select an appropriate nonthermal technology for pineapple juice production and design the intensity required to satisfy the manufacturers, retailers, and consumers.


Assuntos
Ananas , Pasteurização , Pasteurização/métodos , Escherichia coli , Saccharomyces cerevisiae , Sucos de Frutas e Vegetais
6.
Diabetes Obes Metab ; 23(10): 2215-2225, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34105240

RESUMO

AIM: To assess the beneficial metabolic effects of the nonapeptide hormone, arginine vasopressin (AVP), on metabolism. MATERIALS AND METHODS: We exchanged amino acids at position 3 and 8 of AVP, namely phenylalanine and arginine, with those of oxytocin, to generate novel analogues with altered receptor selectivity. Secondary modification by N-terminal acetylation was used to impart stability to circulating endopeptidases. Analogues were screened for degradation, bioactivity in rodent/human clonal beta cells and primary murine islets, together with evaluation of receptor activation profile. RESULTS: Analogue Ac3IV, which lacked effects at the V2 receptors responsible for modulation of fluid balance, was selected as the lead compound for assessment of antidiabetic efficacy in high-fat-fed mice. Twice-daily administration of Ac3IV, or the gold standard control exendin-4, for 22 days, reduced energy intake as well as body weight and fat content. Both interventions decreased circulating glucose levels, enhanced insulin sensitivity, and substantially improved glucose tolerance and related insulin secretion in response to an intraperitoneal or oral glucose challenge. The peptides decreased total- and increased HDL-cholesterol, but only Ac3IV decreased LDL-cholesterol, triglyceride and non-fasting glucagon concentrations. Elevations of islet and beta-cell areas were partially reversed, accompanied by suppressed islet cell proliferation, decreased beta-cell apoptosis and, in the case of exendin-4, also decreased alpha-cell apoptosis. CONCLUSION: AVP-based therapies that exclusively target V1a and V1b receptors may have significant therapeutic potential for the treatment of obesity and related diabetes, and merit further clinical exploration.


Assuntos
Hipoglicemiantes , Insulina , Animais , Arginina Vasopressina , Glucagon , Hipoglicemiantes/uso terapêutico , Lipídeos , Camundongos
7.
Molecules ; 27(1)2021 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-35011245

RESUMO

The aqueous dissolution profile of the isomeric synthetic adamantane phenylalkylamine hydrochlorides I and II was probed. These adducts have shown significant antiproliferative/anticancer activity associated with an analgesic profile against neuropathic pain. They are both devoid of toxic effects and show appreciable enzymatic human plasma stability. The structures of these two compounds have been elucidated using 2D NMR experiments, which were used to study their predominant conformations. Compound II's scaffold appeared more flexible, as shown by the NOE spatial interactions between the alkyl bridge chain, the aromatic rings, and the adamantane nucleus. Conversely, compound I appeared very rigid, as it did not share significant NOEs between the aforementioned structural segments. MD simulations confirmed the NOE results. The aqueous dissolution profile of both molecules fits well with their minimum energy conformers' features, which stem from the NOE data; this was nicely demonstrated, especially in the case of compound II.


Assuntos
Adamantano/química , Analgésicos/química , Antineoplásicos/química , Preparações de Ação Retardada/química , Portadores de Fármacos/química , Derivados da Hipromelose/química , Adamantano/farmacocinética , Analgésicos/farmacocinética , Antineoplásicos/farmacocinética , Fenômenos Biomecânicos , Composição de Medicamentos , Liberação Controlada de Fármacos , Humanos , Técnicas In Vitro , Modelos Químicos , Simulação de Dinâmica Molecular , Relação Estrutura-Atividade
8.
Chembiochem ; 21(17): 2455-2466, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32281223

RESUMO

A quaternary ammonium butylsulfonyl phosphoramidate group (N+) was designed to replace all the phosphates in a G-rich oligodeoxynucleotide d(TG4 T), resulting in a formally charge-neutral zwitterionic N+TG4 T sequence. We evaluated the effects of N+phosphate modifications on the structural, thermodynamic and kinetic properties of the parallel G-quadruplexes (G4) formed by TG4 T and compared them to the properties of the recently published phosphoryl guanidine d(TG4 T) (PG-TG4 T). Using size-exclusion chromatography, we established that, unlike PG-TG4 T, which exists as a mixture of complexes of different molecularity in solution, N+TG4 T forms an individual tetramolecular complex. In contrast to PG modifications that destabilized G4s, the presence of N+ modifications increased thermal stability relative to unmodified [d(TG4 T)]4 . The initial stage of assembly of N+TG4 T proceeded faster in the presence of Na+ than K+ ions and, similarly to PG-TG4 T, was independent of the salt concentration. However, after complex formation exceeded 75 %, N+TG4 T in solution with Na+ showed slower association than with K+ . N+TG4 T could also form G4s in solution with Li+ ions at a very low strand concentration (10 µM); something that has never been reported for the native d(TG4 T). Charge-neutral PG-G4s can invade preformed native G4s, whereas no invasion was observed between N+and native G4s, possibly due to the increased thermal stability of [N+TG4 T]4 . The N+ modification makes d(TG4 T) fully resistant to enzymatic digestion, which could be useful for intracellular application of N+-modified DNA or RNA.


Assuntos
DNA/síntese química , Oligodesoxirribonucleotídeos/química , Fosfatos/química , DNA/química , Quadruplex G , Potássio/química , Sódio/química
9.
Bioorg Med Chem ; 28(19): 115685, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-32912436

RESUMO

Vascularization is one of the key steps for engraftment in regenerative medicine. Previously one of the authors had discovered peptides exhibiting significant angiogenic activities designated AGP and elucidated the active core. For neovascularization basic fibroblast growth factor is used although permeation can be envisaged. The original AGPs did not suffer from this although their half-life times are short because of decomposition by endogenous enzymes. Several new AGP-libraries have been constructed and their enzymatic resistance has been investigated by the use of human umbilical vein endothelial cells to find candidates for clinical applications.


Assuntos
Desenho de Fármacos , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Neovascularização Patológica/tratamento farmacológico , Peptídeos/farmacologia , Células Cultivadas , Relação Dose-Resposta a Droga , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Estrutura Molecular , Peptídeos/síntese química , Peptídeos/química , Relação Estrutura-Atividade
10.
J Food Sci Technol ; 57(9): 3252-3258, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32728273

RESUMO

The use of antimicrobial agents within a matrix, specifically layered compounds, is of growing interest for reducing contamination due to food borne pathogens and deteriorative microorganisms, one of the main health problems worldwide. In this study, zinc layered hydroxide nanoparticles were synthesized as a matrix for nisin immobilization. Layered materials were characterized by X-ray diffraction, Fourier-Transform Infrared and Ultra Violet-Visible spectra, Scanning Electron Microscopy, and by Thermogravimetric Analysis. Thermal, chemical, enzymatic, and biological stabilities were assessed against Lactobacillus brevis as control strain. Free and immobilized nisin in solution were previously subjected to 25 and 121 °C, pH (7, 9) and inactivation with protease before antimicrobial tests that lasted 21 days. Immobilized nisin was found to maintain the activity levels after the protease action while the pure nisin solution lost its activity gradually. Furthermore, immobilized nisin treated at 121 °C and pH 7 showed higher activity than pure nisin after 21 days. These results may support that immobilizing nisin in zinc layered hydroxide salts promoted extended nisin inhibitory activity in solution after thermal, chemical or enzymatic treatments. This research provides an alternative to nisin application that could be used in processes where such operating conditions take place, as in dairy products.

11.
Bioorg Med Chem Lett ; 27(8): 1644-1648, 2017 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-28318942

RESUMO

In this study we report the in vitro activities of four cyclic opioid peptides with various sequence length/macrocycle size and N-methylamino acid residue content. N-Methylated amino acids were incorporated and cyclization was employed to enhance conformational rigidity to various extent. The effect of such modifications on ligand structure and binding properties were studied. The pentapeptide containing one endocyclic and one exocyclic N-methylated amino acid displayed the highest affinity to the mu-opioid receptor. This peptide was also shown to be a full agonist, while the other analogs failed to activate the mu opioid receptor. Results of molecular docking studies provided rationale for the explanation of binding properties on a structural basis.


Assuntos
Analgésicos Opioides/química , Analgésicos Opioides/farmacologia , Peptídeos Opioides/química , Peptídeos Opioides/farmacologia , Receptores Opioides mu/agonistas , Receptores Opioides mu/metabolismo , Sequência de Aminoácidos , Aminoácidos/química , Aminoácidos/farmacologia , Animais , Ciclização , Humanos , Ligantes , Metilação , Simulação de Acoplamento Molecular , Peptídeos Cíclicos/química , Peptídeos Cíclicos/farmacologia , Ratos , Relação Estrutura-Atividade
12.
Prep Biochem Biotechnol ; 47(6): 597-610, 2017 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-28631979

RESUMO

Four strains of Aspergillus (Aspergillus niger CDBB-H-176, A. niger CDBB-H-175, A. niger ATCC 9642, and Aspergillus terreus CDBB-H-194) were used to produce extracellular ß-glucosidase. Using an orthogonal experimental design (L9), we optimized the parameters of culture medium to maximize the activity of ß-glucosidase. The optimal conditions (same for the four strains) were as follows: temperature, 30°C; pH, 6.0; orbital agitation, 200 rpm; concentration of sucrose, 0.5% (w/v). The most productive strain was A. niger CDBB-H-175, with a yield of 701.2 U/mL. In a second stage, we optimized (L18) the concentration of nutrients in the culture medium to determine whether this modification would increase the production of ß-glucosidase. The optimal conditions for A. niger CDBB-H-175 were as follows (%, w/v): NaNO3, 0.3; KCl, 0.3; KH2PO4, 0.15; NH4NO3, 0.1; NH4H2PO4, 0.1; MgSO4 · 7H2O, 0.05; yeast extract, 0.1. The production of ß-glucosidase under these conditions was 1207.9 U/mL. Enzymatic assays were used to characterize the enzyme; the optimum temperature and pH of ß-glucosidase produced by the four selected micro-organisms were found to be 65°C and 5.0, respectively. We determined the Michaelis-Menten constants (Km) only for A. niger CDBB-H-175 and CDBB-H-176; the values were 2.7 and 2.2 mM, respectively.


Assuntos
Aspergillus niger/enzimologia , Fermentação , Microbiologia Industrial/métodos , beta-Glucosidase/metabolismo , Aspergillus niger/citologia , Aspergillus niger/metabolismo , Meios de Cultura/metabolismo , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Temperatura
13.
Mol Pharm ; 13(1): 113-24, 2016 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-26569615

RESUMO

In answering to the challenge of enzymatic unstability of Biopharmaceutics Classification System (BCS) class II drugs, an effective remote loading strategy was developed to successfully incorporate the drug-cyclodextrin (CD) complex into niosomes to modify the release and stability of a drug candidate, pseudolaric acid B (PAB). Judged by binding constants, and combined solubilization effects of pH and CD complexation on PAB at different pH, the complex internalization driven by a transmembrane pH gradient (from 2.0 to 7.4) and the dynamic shifting of PAB-CD complexation equilibrium at this gradient were introduced. The transfer of PAB-CD complex into the internal aqueous phase of niosomes at 60 °C was primarily verified by synchrotron radiation Fourier transform infrared spectroscopy. The remote loading samples behaved as retarded release at pH 5.8, 6.8, and 7.4, for which the stability of PAB in rat plasma was significantly enhanced (about 8.1-fold), in comparison with niosomes prepared by the passive and lipid bilayer loading of PAB. The drug-carrier interaction based release modeling was further fitted, and the convection rate constant (ks) and free energy difference between free and bound states (ΔG) indicated the strongest PAB-carrier interactions in remote loading niosomes. The remote loading strategy also reduced the CD-cholesterol interaction and provided better physical stability of the system. In conclusion, the remote loading of drug-CD complex into niosomes provides advantages to modify the release and enhance the stability of unstable BCS class II drug.


Assuntos
Ciclodextrinas/química , Diterpenos/química , Portadores de Fármacos/química , Lipossomos/química , Animais , Estabilidade de Medicamentos , Concentração de Íons de Hidrogênio , Ratos
14.
J Pept Sci ; 22(4): 222-7, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27028206

RESUMO

In this study, proteinogenic amino acids residues of dimeric dermorphin pentapeptides were replaced by the corresponding ß(3)-homo-amino acids. The potency and selectivity of hybrid α/ß dimeric dermorphin pentapeptides were evaluated by competetive receptor binding assay in the rat brain using [3H]DAMGO (a µ ligand) and [3H]DELT (a δ ligand). Tha analog containing ß(3)-homo-Tyr in place of Tyr (Tyr-D-Ala-Phe-Gly-ß(3)-homo-Tyr-NH-)2 showed good µ receptor affinity and selectivity (IC50 = 0.302, IC50 ratio µ/δ = 68) and enzymatic stability in human plasma.


Assuntos
Aminobutiratos/química , Peptídeos Opioides/síntese química , Tirosina/análogos & derivados , Tirosina/química , Animais , Ligação Competitiva , Estabilidade de Medicamentos , Humanos , Concentração Inibidora 50 , Masculino , Peptídeos Opioides/metabolismo , Peptídeos Opioides/farmacologia , Ligação Proteica , Ratos , Ratos Wistar , Receptores Opioides/metabolismo
15.
J Sci Food Agric ; 95(2): 329-36, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24798991

RESUMO

BACKGROUND: The molecular configuration, molecular weight distribution and thermal transition enthalpy (ΔH) of grass carp skin (GCS) collagens after heat treatment under different conditions were measured using circular dichroism, gel filtration chromatography and differential scanning calorimetry (DSC). The enzymatic stability of collagen was evaluated using different enzymes, while the ability to form fibrils in vitro was assessed by morphological observation of collagen fibrils and turbidity testing. RESULTS: The ΔH values, in-solution molecular aggregation and the stability to enzymatic hydrolysis of GCS collagen decreased irreversibly and progressively with the duration of heat treatment at 33 °C, which was the onset endothermic temperature obtained from the DSC curve. A strong positive linear correlation between the enzymatic sensitivity of collagen and the degree of thermal denaturation was found. A decrease in fibril diameter and D-periodicity length with denaturation could also be observed in the SEM and TEM images. CONCLUSION: The onset endothermic temperature (To ) rather than the denaturation temperature (Td ) is the threshold temperature for configurational stability of GCS collagen in acidic solution, and the biological properties would obviously change if the collagen was heat treated at this temperature.


Assuntos
Carpas , Colágeno/química , Proteínas de Peixes/química , Temperatura Alta , Desnaturação Proteica , Pele/química , Ácidos , Animais , Materiais Biocompatíveis/química , Varredura Diferencial de Calorimetria , Dicroísmo Circular , Enzimas , Matriz Extracelular , Hidrólise , Técnicas In Vitro , Soluções , Termodinâmica
16.
Bioorg Med Chem ; 22(3): 997-1002, 2014 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-24411200

RESUMO

In this Letter, we investigated the binding properties towards nucleic acids of a thymine-functionalized oligolysine, composed of nucleobase-bearing amino acid moieties and underivatized l-lysine residues alternate in the backbone. The basic nucleopeptide proved to be well soluble in water and able to interact with both DNA and RNA, as suggested by circular dichroism, UV and surface plasmon resonance studies performed on the thymine-containing oligomer with both adenine-containing DNA (dA12) and RNA (rA12 and poly rA) molecules. In both cases the thymine-functionalized oligolysine was proven to form complexes characterized by a 1:1 T/A stoichiometric ratio, as evidenced by CD titration. UV melting experiments revealed that the complex formed between the homothymine oligolysine and rA12 RNA was more stable than the complex with dA12 DNA probably due to the additional H-bonding of the 2'-OH groups in RNA, that reinforces the overall interaction with the nucleopeptide. Finally, human serum stability assays were conducted on the thymine-bearing nucleopeptide which showed a half-life of 45min.


Assuntos
DNA/metabolismo , Lisina/química , Peptídeos/química , Peptídeos/metabolismo , RNA/metabolismo , Timina/química , Dicroísmo Circular , DNA/química , Meia-Vida , Humanos , RNA/química , Soro/química , Solubilidade , Ressonância de Plasmônio de Superfície
17.
J Pept Sci ; 20(12): 945-51, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25316570

RESUMO

Currently, novel antibiotics are urgently required to combat the emergence of drug-resistant bacteria. Antimicrobial peptides with membrane-lytic mechanism of action have attracted considerable interest. Anoplin, a natural α-helical amphiphilic antimicrobial peptide, is an ideal research template because of its short sequence. In this study, we designed and synthesized a group of analogues of anoplin. Among these analogues, anoplin-4 composed of D-amino acids displayed the highest antimicrobial activity due to increased charge, hydrophobicity and amphiphilicity. Gratifyingly, anoplin-4 showed low toxicity to host cells, indicating high bacterial selectivity. Furthermore, the mortality rate of mice infected with Escherichia coli was significantly reduced by anoplin-4 treatment relative to anoplin. In conclusion, anoplin-4 is a novel anoplin analogue with high antimicrobial activity and enzymatic stability, which may represent a potent agent for the treatment of infection.


Assuntos
Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Peptídeos Catiônicos Antimicrobianos/química , Peptídeos Catiônicos Antimicrobianos/farmacologia , Venenos de Vespas/química , Venenos de Vespas/farmacologia , Sequência de Aminoácidos , Permeabilidade da Membrana Celular/efeitos dos fármacos , Desenho de Fármacos , Escherichia coli/efeitos dos fármacos , Escherichia coli/ultraestrutura , Microscopia Eletrônica de Varredura , Dados de Sequência Molecular , Proteólise
18.
Appl Biochem Biotechnol ; 196(8): 5283-5300, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38153653

RESUMO

This study aimed to fabricate gum Arabic (GA)-coated Fe3O4 nanoparticles bearing numerous active aldehyde groups on their surface, followed by an assessment of their capability as a magnetic support for the covalent immobilization of the trypsin enzyme for the first time. FT-IR, XRD, TGA, and SEM results demonstrated the successful synthesis of GA-coated Fe3O4 nanoparticles, along with the covalent immobilization of the enzyme onto the support. Immobilization enhanced the relative enzymatic activity across a range of aqueous solution pH levels (ranging from 4 to 11) and temperatures (ranging from 20 to 80 °C) without altering the optimum pH and temperature for trypsin activity. Kinetic studies using Michaelis-Menten plots revealed changes in kinetic parameters, including a lower Vmax and higher Km for immobilized trypsin compared to the free enzyme. The immobilization onto magnetic gum Arabic nanoparticles resulted in an improved stability of trypsin in the presence of various solvents, maintaining a stability order comparable to that of the free enzyme due to the stabilizing effect of the support. The reusability results showed that the immobilized enzyme can retain over 93% of its activity for up to 15 cycles.


Assuntos
Estabilidade Enzimática , Enzimas Imobilizadas , Goma Arábica , Temperatura , Tripsina , Enzimas Imobilizadas/química , Tripsina/química , Goma Arábica/química , Concentração de Íons de Hidrogênio , Nanopartículas de Magnetita/química , Cinética , Espectroscopia de Infravermelho com Transformada de Fourier
19.
Food Res Int ; 191: 114662, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39059935

RESUMO

This work explored the impact of ultrasound (US) on the activity, stability, and macrostructural conformation of cyclodextrin glycosyltransferase (CGTase) and how these changes could maximize the production of ß-cyclodextrins (ß-CDs). The results showed that ultrasonic pretreatment (20 kHz and 38 W/L) at pH 6.0 promoted increased enzymatic activity. Specifically, after sonication at 25 °C/30 min, there was a maximum activity increase of 93 % and 68 % when biocatalysis was carried out at 25 and 55 °C, respectively. For activity measured at 80 °C, maximum increase (31 %) was observed after sonication at 25 °C/60 min. Comparatively, US pretreatment at low pH (pH = 4.0) resulted in a lower activity increase (max. 28 %). These activation levels were maintained after 24 h of storage at 8 °C, suggesting that changes on CGTase after ultrasonic pretreatment were not transitory. These pretreatments altered the conformational structure of CGTase, revealed by an up to 11 % increase in intrinsic fluorescence intensity, and resulted in macrostructural modifications, such as a decrease in particle size and polydispersion index (up to 85 % and 45.8 %, respectively). Therefore, the sonication of CGTase under specific conditions of pH, time, and temperature (especially at pH 6.0/ 30 min/ 25 °C) promotes macrostructural changes in CGTase that induce enzyme activation and, consequently, higher production of ß-CDs.


Assuntos
Estabilidade Enzimática , Glucosiltransferases , beta-Ciclodextrinas , Glucosiltransferases/metabolismo , beta-Ciclodextrinas/química , Concentração de Íons de Hidrogênio , Sonicação , Temperatura , Ultrassom
20.
Front Chem ; 12: 1436049, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39148667

RESUMO

Stabilized enzymes are crucial for the industrial application of biocatalysis due to their enhanced operational stability, which leads to prolonged enzyme activity, cost-efficiency and consequently scalability of biocatalytic processes. Over the past decade, numerous studies have demonstrated that deep eutectic solvents (DES) are excellent enzyme stabilizers. However, the search for an optimal DES has primarily relied on trial-and-error methods, lacking systematic exploration of DES structure-activity relationships. Therefore, this study aims to rationally design DES to stabilize various dehydrogenases through extensive experimental screening, followed by the development of a straightforward and reliable mathematical model to predict the efficacy of DES in enzyme stabilization. A total of 28 DES were tested for their ability to stabilize three dehydrogenases at 30°C: (S)-alcohol dehydrogenase from Rhodococcus ruber (ADH-A), (R)-alcohol dehydrogenase from Lactobacillus kefir (Lk-ADH) and glucose dehydrogenase from Bacillus megaterium (GDH). The residual activity of these enzymes in the presence of DES was quantified using first-order kinetic models. The screening revealed that DES based on polyols serve as promising stabilizing environments for the three tested dehydrogenases, particularly for the enzymes Lk-ADH and GDH, which are intrinsically unstable in aqueous environments. In glycerol-based DES, increases in enzyme half-life of up to 175-fold for Lk-ADH and 60-fold for GDH were observed compared to reference buffers. Furthermore, to establish the relationship between the enzyme inactivation rate constants and DES descriptors generated by the Conductor-like Screening Model for Real Solvents, artificial neural network models were developed. The models for ADH-A and GDH showed high efficiency and reliability (R2 > 0.75) for in silico screening of the enzyme inactivation rate constants based on DES descriptors. In conclusion, these results highlight the significant potential of the integrated experimental and in silico approach for the rational design of DES tailored to stabilize enzymes.

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