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1.
J Agric Food Chem ; 68(4): 1157-1167, 2020 Jan 29.
Artículo en Inglés | MEDLINE | ID: mdl-31917922

RESUMEN

To investigate the alterations of egg yolk protein abundances and their phosphorylation status at different storage temperatures, a comparative quantitative study of unfertilized chicken egg yolk after 15 days of storage at 4 and 37 °C was performed. Altogether, 445 proteins were identified in our study, of which the abundances of 154 proteins were significantly changed when comparing high-temperature storage with low-temperature storage, including 42 up-regulated and 112 down-regulated proteins. In the phosphoproteome, we identified a total of 137 phosphorylated sites on 326 peptides corresponding to 51 proteins. The results showed that the degree of phosphorylation for most egg yolk proteins was enhanced during high-temperature storage. Furthermore, GO analysis indicated that these phosphoproteins of egg yolk may be closely related to the binding, catalysis, and transport functions. The results provide further insights into the effect of storage temperature on egg proteome changes and their phosphorylation level. Moreover, this study can provide a theoretical basis for the improvement of egg quality during storage by phosphorylation modification in the food industry.


Asunto(s)
Proteínas del Huevo/química , Fosfoproteínas/química , Animales , Pollos , Cromatografía Líquida de Alta Presión , Proteínas del Huevo/metabolismo , Almacenamiento de Alimentos , Espectrometría de Masas , Péptidos/química , Péptidos/metabolismo , Fosfoproteínas/metabolismo , Proteoma/química , Proteoma/metabolismo , Proteómica , Temperatura Ambiental
2.
Pharm Res ; 37(2): 30, 2020 Jan 08.
Artículo en Inglés | MEDLINE | ID: mdl-31915939

RESUMEN

PURPOSE: mRNA has recently emerged as a potent therapeutics and requires safe and effective delivery carriers, particularly prone to address its issues of poor stability and escape from endosomes. In this context, we designed poly(D,L-lactide) (PLA)-based micelles with N-succinimidyl (NS) ester decorated hydrophilic hairy corona to trap/couple a cationic fusogenic peptide and further complex mRNA. METHODS: Two strategies were investigated, namely (i) sequential immobilization of peptide and mRNA onto the micelles (layer-by-layer, LbL) or (ii) direct immobilization of peptide-mRNA pre-complex (PC) on the micelles. After characterization by means of size, surface charge, peptide/mRNA coupling/complexation and mRNA serum stability, carrier cytotoxicity and transfection capacity were evaluated with dendritic cells (DCs) using both GFP and luciferase mRNAs. RESULTS: Whatever the approach used, the micellar assemblies afforded full protection of mRNA in serum while the peptide-mRNA complex yielded complete mRNA degradation. In addition, the micellar assemblies allowed to significantly reduce the toxicity observed with the peptide-mRNA complex. They successfully transfected hard-to transfect DCs, with a superior efficiency for the LbL made ones (whatever mRNAs studied) showing the impact of the elaboration process on the carrier properties. CONCLUSIONS: These results show the relevance and potential of this new PLA/peptide based micelle platform to improve mRNA stability and delivery, while offering the possibility of further multifunctionality through PLA core encapsulation.


Asunto(s)
Portadores de Fármacos/química , Péptidos/química , Poliésteres/química , Povidona/análogos & derivados , ARN Mensajero/química , Animales , Línea Celular , Supervivencia Celular , Estabilidad de Medicamentos , Expresión Génica , Interacciones Hidrofóbicas e Hidrofílicas , Ratones , Micelas , Povidona/química , ARN Mensajero/genética , Transfección
3.
Chem Commun (Camb) ; 56(3): 399-402, 2020 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-31820751

RESUMEN

A combinatorial approach using a one-bead-one-compound method and a screening based on a SOD-activity assay was set up for the discovery of an efficient peptidyl copper complex. The complex exhibited good stability constants, suitable redox potentials and excellent intrinsic activity. This complex was further assayed in cells for its antioxidant properties and showed beneficial effects when cells were subjected to oxidative stress.


Asunto(s)
Materiales Biocompatibles/metabolismo , Cobre/química , Péptidos/química , Secuencia de Aminoácidos , Materiales Biocompatibles/química , Materiales Biocompatibles/farmacología , Colon/citología , Colon/efectos de los fármacos , Colon/metabolismo , Cobre/metabolismo , Células HT29 , Humanos , Interleucina-8/metabolismo , Lipopolisacáridos/toxicidad , Estrés Oxidativo/efectos de los fármacos , Péptidos/metabolismo , Superóxido Dismutasa/metabolismo
4.
Chem Commun (Camb) ; 56(3): 356-359, 2020 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-31825398

RESUMEN

A facile and scalable strategy for the quick library synthesis of linear-, hinged-, star-, and cyclic-polypeptides with broad-spectrum antimicrobial activity has been reported. The topologically nanoengineered polypeptides show superior antimicrobial activity against Gram-positive and Gram-negative bacteria and low toxicity, allowing screening of architectural polypeptides as mimics of host defense peptides for antimicrobials.


Asunto(s)
Antiinfecciosos/síntesis química , Péptidos/química , Animales , Antiinfecciosos/química , Antiinfecciosos/farmacología , Supervivencia Celular/efectos de los fármacos , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Grampositivas/efectos de los fármacos , Ratones , Pruebas de Sensibilidad Microbiana , Microscopía Confocal , Células 3T3 NIH , Nanotecnología , Péptidos/síntesis química , Péptidos/farmacología
5.
Chem Commun (Camb) ; 56(1): 74-77, 2020 Jan 04.
Artículo en Inglés | MEDLINE | ID: mdl-31790117

RESUMEN

We developed a new method for the de novo formation of fluorophores based on citrate (DNFC) in biological samples. Use of an amide coupling reagent and microwave irradiation greatly facilitates the fluorophore formation on peptides and proteins with N-terminal cysteine or serine. Since N-terminal cysteine and serine can form thiazolopyridone- or oxazolopyridone-based fluorophores emitting blue and green fluorescence, respectively, by the DNFC staining, each organelle, cell and tissue exhibited a characteristic fluorescence distribution. The DNFC staining is able to provide a new potential protocol for future cell imaging, histology and diagnosis.


Asunto(s)
Colorantes Fluorescentes/metabolismo , Sondas Moleculares/metabolismo , Péptidos/metabolismo , Proteínas/metabolismo , Animales , Línea Celular Tumoral , Ácido Cítrico/metabolismo , Cisteína/química , Fluorescencia , Colorantes Fluorescentes/química , Células HEK293 , Humanos , Ratones , Microscopía Confocal/métodos , Microscopía Fluorescente/métodos , Sondas Moleculares/química , Células 3T3 NIH , Péptidos/química , Prueba de Estudio Conceptual , Proteínas/química , Piridonas/química , Piridonas/metabolismo , Serina/química , Tiazoles/química , Tiazoles/metabolismo
6.
J Sci Food Agric ; 100(3): 1246-1255, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31696520

RESUMEN

BACKGROUND: Chinese mutton ham is a dry-cured meat product with a long ripening time. The aim of this study was to identify and characterize antioxidant peptides from Chinese mutton ham. RESULTS: Mutton ham peptides (MHPs) were purified by gel filtration, anion exchange and reversed-phase high-performance liquid chromatography steps. The 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) free radical scavenging capacity was used to guide the purification of MHPs. Three antioxidant peptides were identified by liquid chromatography with tandem mass spectrometry (LC-MS/MS) as Met-Trp-Thr-Asp (MWTD), Ala-Pro-Tyr-Met-Met (APYMM) and Phe-Trp-Ile-Ile-Glu (FWIIE), with molecular weights 551.61, 611.76, and 706.84 Da, respectively. Among them, APYMM exhibited the highest ABTS radical scavenging activity. The three peptides had the ability to inhibit lipid oxidation and Fenton's reagent-induced protein oxidation and DNA damage. After simulated gastrointestinal digestion, FWIIE and APYMM showed increased antioxidant activity, while MWTD showed decreased activity. CONCLUSION: Three novel peptides isolated from Chinese mutton ham had strong biological activity. Chinese mutton ham is potentially a functional food and an excellent source of natural antioxidants. © 2019 Society of Chemical Industry.


Asunto(s)
Antioxidantes/química , Productos de la Carne/análisis , Péptidos/química , Secuencia de Aminoácidos , Animales , China , Cromatografía Liquida , Lípidos/química , Oxidación-Reducción , Mapeo Peptídico , Porcinos , Espectrometría de Masas en Tándem
7.
Chemistry ; 26(1): 165-170, 2020 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-31691395

RESUMEN

Phosphorylation is an important post-translational modification on proteins involved in many cellular processes; however, understanding of the regulation and mechanisms of global phosphorylation remains limited. Herein, we utilize self-assembled monolayers on gold for matrix-assisted laser desorption/ionization mass spectrometry (SAMDI-MS) with three phosphorylated peptide arrays to profile global phosphatase activity in cell lysates derived from five mammalian cell lines. Our results reveal significant differences in the activities of protein phosphatases on phospho- serine, threonine, and tyrosine substrates and suggest that phosphatases play a much larger role in the regulation of global phosphorylation on proteins than previously understood.


Asunto(s)
Péptidos/química , Monoéster Fosfórico Hidrolasas/metabolismo , Análisis por Matrices de Proteínas/métodos , Animales , Línea Celular , Humanos , Ratones , Péptidos/metabolismo , Monoéster Fosfórico Hidrolasas/química , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , Especificidad por Sustrato
8.
Chemistry ; 26(1): 249-258, 2020 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-31710732

RESUMEN

Superoxide dismutases (SODs) are highly efficient enzymes for superoxide dismutation and the first line of defense against oxidative stress. These metalloproteins contain a redox-active metal ion in their active site (Mn, Cu, Fe, Ni) with a tightly controlled reduction potential found in a close range around the optimal value of 0.36 V versus the normal hydrogen electrode (NHE). Rationally designed proteins with well-defined three-dimensional structures offer new opportunities for obtaining functional SOD mimics. Here, we explore four different copper-binding scaffolds: H3 (His3 ), H4 (His4 ), H2 DH (His3 Asp with two His and one Asp in the same plane) and H3 D (His3 Asp with three His in the same plane) by using the scaffold of the de novo protein GRα3 D. EPR and XAS analysis of the resulting copper complexes demonstrates that they are good CuII -bound structural mimics of Cu-only SODs. Furthermore, all the complexes exhibit SOD activity, though three orders of magnitude slower than the native enzyme, making them the first de novo copper SOD mimics.


Asunto(s)
Cobre/química , Metaloproteínas/química , Péptidos/química , Secuencia de Aminoácidos , Cobre/metabolismo , Espectroscopía de Resonancia por Spin del Electrón , Pruebas de Enzimas , Metaloproteínas/metabolismo , Péptidos/metabolismo , Estabilidad Proteica , Superóxido Dismutasa/química , Superóxido Dismutasa/metabolismo , Temperatura Ambiental , Termodinámica
9.
J Chem Theory Comput ; 16(1): 528-552, 2020 Jan 14.
Artículo en Inglés | MEDLINE | ID: mdl-31714766

RESUMEN

Molecular dynamics (MD) simulations have become increasingly popular in studying the motions and functions of biomolecules. The accuracy of the simulation, however, is highly determined by the molecular mechanics (MM) force field (FF), a set of functions with adjustable parameters to compute the potential energies from atomic positions. However, the overall quality of the FF, such as our previously published ff99SB and ff14SB, can be limited by assumptions that were made years ago. In the updated model presented here (ff19SB), we have significantly improved the backbone profiles for all 20 amino acids. We fit coupled φ/ψ parameters using 2D φ/ψ conformational scans for multiple amino acids, using as reference data the entire 2D quantum mechanics (QM) energy surface. We address the polarization inconsistency during dihedral parameter fitting by using both QM and MM in aqueous solution. Finally, we examine possible dependency of the backbone fitting on side chain rotamer. To extensively validate ff19SB parameters, and to compare to results using other Amber models, we have performed a total of ∼5 ms MD simulations in explicit solvent. Our results show that after amino-acid-specific training against QM data with solvent polarization, ff19SB not only reproduces the differences in amino-acid-specific Protein Data Bank (PDB) Ramachandran maps better but also shows significantly improved capability to differentiate amino-acid-dependent properties such as helical propensities. We also conclude that an inherent underestimation of helicity is present in ff14SB, which is (inexactly) compensated for by an increase in helical content driven by the TIP3P bias toward overly compact structures. In summary, ff19SB, when combined with a more accurate water model such as OPC, should have better predictive power for modeling sequence-specific behavior, protein mutations, and also rational protein design. Of the explicit water models tested here, we recommend use of OPC with ff19SB.


Asunto(s)
Aminoácidos/química , Péptidos/química , Proteínas/química , Agua/química , Simulación de Dinámica Molecular , Conformación Proteica , Estabilidad Proteica , Teoría Cuántica , Termodinámica
10.
J Sci Food Agric ; 100(3): 1320-1327, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31742702

RESUMEN

BACKGROUND: Potato protein hydrolysates (PPHs) were preparedwith Alcalase on intact potato protein isolates (PPI), with differenthydrolysis times (0.5-4 h), and functional and conformational properties of resultant hydrolysates were investigated. RESULTS: The degree of hydrolysis changed during incubation. Peptide bond cleavage increased and hydrolysis progressed rapidly. Gel electrophoresis showed that, by increasing the hydrolysis time, peptides with an apparent molecular weight below 20 kDa increased. It also revealed that, among potato protein components, patatin was more sensitive to Alcalase® hydrolysis than protease inhibitors. Enzymatic hydrolysis significantly enhanced the solubility and foam capacity of PPHs, but impaired foam stability (P < 0.05). Limited enzymatic hydrolysates (0.5PPH) at the interface improved the emulsion activity and stability index. These emulsions also had the smallest z-average and polydispersity index and showed the highest zeta potential. Fourier-transform infrared spectrometry (FTIR) analysis indicated extensive disruption of hydrogen bonds in PPHs, besides augmentation of α-helices and ß-turns, and a decline in the ß-sheets in the secondary structure of the PPHs was shown. CONCLUSION: Potato protein isolate, especially 0.5PPH, has good functional and conformational properties. Overall, our results provide new insights into the use of potato protein hydrolysates as a functional food component in the food industry. © 2019 Society of Chemical Industry.


Asunto(s)
Proteínas de Plantas/química , Solanum tuberosum/química , Subtilisinas/química , Biocatálisis , Manipulación de Alimentos , Hidrólisis , Peso Molecular , Péptidos/química , Hidrolisados de Proteína/química , Solubilidad
11.
Chemistry ; 26(2): 379-383, 2020 Jan 07.
Artículo en Inglés | MEDLINE | ID: mdl-31609031

RESUMEN

Peptide alcohols are clinically important compounds that are underexplored in structure-activity relationship (SAR) studies in drug discovery. One reason for this underutilization is that current syntheses are laborious and time consuming. Herein, we describe the preparation and utility of Rink, Ramage, and Sieber-chloride resins, which enables the use of a general, easy and practical method for the attachment of fluorenylmethoxycarbonyl (Fmoc)-amino alcohols to a solid support, in the synthesis of peptide alcohols. This method is the first straightforward Fmoc/tBu synthesis of peptide alcohols starting from a pre-loaded resin. The synthesized peptide alcohols can be detached from the linkers through conventional methods. Treatment with trifluoroacetic acid (TFA) (95 %) and scavengers such as triisopropylsilane and water for 2 h is sufficient to obtain a fully deprotected peptide alcohol, while treatment with 20 % hexafluoroisopropanol in dichloromethane renders a fully protected peptide alcohol that can be further modified at the C-terminus. As examples, the new resins were used in straightforward, relatively rapid syntheses of the peptide alcohols octreotide, alamethicin, and a segment of trichogin GA IV, as well as the first synthesis of stapled peptide alcohols.


Asunto(s)
Amino Alcoholes/química , Péptidos/química , Péptidos/síntesis química , Fenilalanina/análogos & derivados , Fenilalanina/química , Poliestirenos/química , Ácido Trifluoroacético/química
12.
J Sci Food Agric ; 100(3): 936-944, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31487041

RESUMEN

BACKGROUND: This study investigates the efficacy of short peptides secreted by Bacillus subtilis for fungal inhibition in fresh-cut pumpkin and for maintaining its shelf life. RESULTS: Low-molecular-weight filtrate (LC < 1000 Da) of B. subtilis culture (BC) significantly lowered the total number of molds on fresh-cut pumpkin compared with the untreated control and a BC group after storage. Low-molecular-weight filtrate prevented the deterioration of sensory quality in a pumpkin incision, and reduced pectinase activity. It also inhibited the growth of Phytophthora capsici and Penicillium chrysogenum, and the activity of ß-1,3-glucan synthase (GS) secreted by both molds. Fifty-seven GS-inhibiting peptides were screened from 95 LC peptides with two to five amino acid residues. The two most potent peptides, AWYW and HWWY, had strongly suppressive effects on the growth of P. capsici and P. chrysogenum. CONCLUSION: Our study demonstrated that short peptides present in B. subtilis culture can play an important role in the maintenance of fresh-cut pumpkin by suppressing fungal growth. © 2019 Society of Chemical Industry.


Asunto(s)
Bacillus subtilis/química , Cucurbita/microbiología , Hongos/efectos de los fármacos , Fungicidas Industriales/farmacología , Péptidos/farmacología , Bacillus subtilis/metabolismo , Frutas/microbiología , Hongos/crecimiento & desarrollo , Fungicidas Industriales/química , Fungicidas Industriales/metabolismo , Penicillium chrysogenum/efectos de los fármacos , Penicillium chrysogenum/crecimiento & desarrollo , Péptidos/química , Péptidos/metabolismo , Phytophthora/efectos de los fármacos , Phytophthora/crecimiento & desarrollo , Enfermedades de las Plantas/microbiología
13.
J Sci Food Agric ; 100(1): 59-73, 2020 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-31435933

RESUMEN

BACKGROUND: Jiuzao is the residue after Bajiu distillation which is usually used as forage for livestock. However, it is not fully utilized yet considering the content of protein remained. The present study aimed to isolate antioxidant peptides from Jiuzao protein hydrolysates, then add these peptides into Baijiu product to enhance the healthy value of Baiju. Meanwhile environmental pollution caused by massive Jiuzao can be mitigated indirectly. RESULTS: Four peptides Ala-Tyr-Ile(Leu) (AYI(L)) and Asp-Arg-Glu-Ile(Leu) (DREI(L)) were identified from Jiuzao protein hydrolysates, the extraction contents of AYI + AYL and DREI + DREL were 896.10 and 110.51 mg kg-1 Jiuzao, respectively. On the one hand, antioxidant activities of these peptides were investigated. For in vitro antioxidant assays, AYI, AYL and DREI exhibited strong capacities in oxygen radical absorbance capacity (ORAC) assay. Furthermore, three levels of four peptides were assessed by 2,2'-azobis(2-methylpropanimidamidine) (AAPH)-induced HepG2 cells model. The results showed that these peptides exerted a degree of antioxidant activities in cells. Meanwhile, selected peptides concentrations according to cell assays remined at effective doses after in vitro digestion. On the other hand, the influence of these four peptides on the characteristic aroma compounds in Baijiu was studied. Most characteristic aroma compounds releases were increased with the addition of peptides. CONCLUSION: In the study, antioxidant activities of peptides were evaluated, the feasibility of utilizing Jiuzao protein hydrolysates to obtain beneficial peptides was also proved. Healthy effect of Baijiu or other food can be increased by adding these functional substances. The findings might contribute to food application and Baijiu industries. © 2019 Society of Chemical Industry.


Asunto(s)
Antioxidantes/química , Péptidos/química , Hidrolisados de Proteína/química , Residuos/análisis , Vino/análisis , Antioxidantes/farmacología , Supervivencia Celular/efectos de los fármacos , Células Hep G2 , Humanos , Péptidos/farmacología , Hidrolisados de Proteína/farmacología
14.
J Chem Theory Comput ; 16(1): 601-611, 2020 Jan 14.
Artículo en Inglés | MEDLINE | ID: mdl-31841332

RESUMEN

Extensive benchmarking calculations are presented to assess the accuracy of the standard approximate coupled cluster singles and doubles method (CC2) in studying ππ* excited states properties of model protein chains containing a phenylalanine residue, namely capped peptides, whose ground state conformers adopt the prototypical secondary structural features of proteins. First, the dependence with the basis set of the CC2 excitation energies, CC2 geometry optimizations, and amide A region frequencies of the lowest ππ* excited state in a reference system, the N-acetylphenylalaninylamide, are investigated, and the results are compared with experimental data. Second, at the best level of theory determined, the CC2/aug(N,O,π)-cc-pVDZ//CC2/cc-pVDZ level, a series of capped peptides of increasing size and containing residues of different nature are investigated. Along the series, compared to the experimental values, a mean absolute error of 0.10 eV is achieved for the 0-0 transition energies with a systematic overestimation. In addition, mode-dependent linear scaling functions for the calculated frequencies of the amide A region have been determined from the set of 95 experimental frequencies available; they lead to a quantitative simulation of the observed shifts of the amide A region frequencies upon ππ* excitation (root-mean-square deviation of 5 cm-1). These results confirm the reliability of the CC2 method to characterize the lowest ππ* excited state of such medium-sized systems, emphasizing this class of theoretical approaches as a relevant spectroscopic tool, including for tasks as difficult as conformational assignment.


Asunto(s)
Péptidos/química , Fenilalanina/química , Proteínas/química , Algoritmos , Modelos Moleculares , Teoría Cuántica , Termodinámica
15.
Food Chem ; 306: 125613, 2020 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-31610331

RESUMEN

Reduction of bitter taste in protein hydrolysates is a challenging task. The aim of this study was to apply a simple two-step approach to prepare low bitter hydrolysates and investigate the influence of peptide modifications on taste characteristics. Protein hydrolysates were prepared from porcine muscle and plasma through simultaneous hydrolysis using endo- and exo-peptidases combined with peptide glycation by glucosamine (GlcN). Spectroscopic analysis and quantification of major alpha-dicarbonyl compounds (α-DCs) indicated the relatively low extent of Maillard reaction in GlcN-glycated protein hydrolysates. Thermal degradation of high MW peptides (>10 kDa) might play a major role in Maillard reaction, reflected by the formation of more Maillard reacted peptides (1-5 kDa), especially in plasma samples. Sensory evaluation indicated that glycation by GlcN can alter taste profiles of protein hydrolysates, which may be attributed to the formation of Maillard reacted peptides and peptide modifications revealed by LC-MS/MS analysis.


Asunto(s)
Exopeptidasas/química , Músculo Esquelético/química , Gusto , Animales , Aspergillus oryzae/enzimología , Exopeptidasas/metabolismo , Glucosamina/química , Glucosamina/metabolismo , Glicosilación , Hidrólisis , Reacción de Maillard , Músculo Esquelético/metabolismo , Péptidos/química , Péptidos/metabolismo , Hidrolisados de Proteína/química , Porcinos
16.
Food Chem ; 306: 125602, 2020 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-31629969

RESUMEN

Effects of high-pressure treatments (HPT, 100-300 MPa, 9 min, 25 °C) on the in vitro digestibility of gel-type meat products were studied using a simulated digestion-model. In vitro digestibilities of the cooked rabbit meat batters throughout the simulated oral-, gastric-, and intestinal-phases were determined. Peptides in the intestinal digesta were identified via Mass Spectrometer. Results revealed that in vitro digestibilities of HPT-samples were higher than the control (1.98%, 6.13% and 61.31% for oral-, gastric- and intestinal-phase respectively) throughout the digestion (P < 0.05). Alterations of the peptide profiles were induced by HPT, showing HPT-specific patterns of mutual peptides in the digestive products. Coupled with the identifications of salt-soluble proteins from raw batters, it was confirmed that myofibrillar proteins account for the major contribution to the HPT-induced changes. The results indicated that HPT can potentially be an effective technology to improve the digestibility of meat products.


Asunto(s)
Productos de la Carne/análisis , Péptidos/química , Animales , Culinaria , Presión , Proteolisis , Conejos
17.
Biophys Chem ; 257: 106280, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-31877450

RESUMEN

High pressure acts as a mild and non-destructive activation mode for chemical reactions. However, in the context of organo-/biocatalysis, high pressure activation, has not been investigated systematically, although there are significant benefits such as rate acceleration, increased selectivity and the possibility of suppressing side product formation. The influence of hydrostatic pressure in solution on the catalytic performance of enzymes and small molecule organocatalysts such as amino acids, peptides, amines, cinchona alkaloids and thioureas is evaluated in this review, taking reactivity and selectivity as a probe to identify pressure effects on biomolecules.


Asunto(s)
Aminoácidos/química , Alcaloides de Cinchona/química , Péptidos/química , Presión , Catálisis , Reacción de Cicloadición , Enzimas/química , Enzimas/metabolismo , Soluciones/química , Tiourea/análogos & derivados
18.
Phys Chem Chem Phys ; 22(3): 1359-1370, 2020 Jan 22.
Artículo en Inglés | MEDLINE | ID: mdl-31854397

RESUMEN

Depending on the amino acid sequence, as well as the local environment, some peptides have the capability to fold into multiple secondary structures. Conformational switching between such structures is a key element of protein folding and aggregation. Specifically, understanding the molecular mechanism underlying the transition from an α-helix to a ß-hairpin is critical because it is thought to be a harbinger of amyloid assembly. In this study, we explore the energy landscape for an 18-residue peptide (DP5), designed by Araki and Tamura to exhibit equal propensities for the α-helical and ß-hairpin forms. We find that the degeneracy is encoded in the multifunnel nature of the underlying free energy landscape. In agreement with experiment, we also observe that mutation of tyrosine at position 12 to serine shifts the equilibrium in favor of the α-helix conformation, by altering the landscape topography. The transition from the α-helix to the ß-hairpin is a complex stepwise process, and occurs via collapsed coil-like intermediates. Our findings suggest that even a single mutation can tune the emergent features of the landscape, providing an efficient route to protein design. Interestingly, the transition pathways for the conformational switch seem to be minimally perturbed upon mutation, suggesting that there could be universal microscopic features that are conserved among different switch-competent protein sequences.


Asunto(s)
Péptidos/química , Mutación , Péptidos/genética , Conformación Proteica en Hélice alfa/genética , Conformación Proteica en Lámina beta/genética
19.
Phys Chem Chem Phys ; 22(3): 1392-1399, 2020 Jan 21.
Artículo en Inglés | MEDLINE | ID: mdl-31859314

RESUMEN

Detailed knowledge of intramolecular hydrogen bonds, including their nanomechanics, in a peptide secondary structure is crucial for understanding mechanisms of numerous biochemical processes. Single-molecule force spectroscopy has become a powerful tool to study directly the mechanical properties of single biopolymers and monitoring the hydrogen bonds. However, the interpretation of such experiments, due to their poor temporal resolution relative to the rate of intramolecular dynamics, requires the support of molecular simulations. In this work, we provide a methodology for determining the kinetic and energetic characteristics of hydrogen bonds in a template model of the protein secondary structure. Our approach, based on the steered molecular dynamics method, employs dynamic force spectroscopy calculations and uses two advanced theoretical models of force-induced unbinding. A systematic analysis of the simulated data with these models allowed for quantitative characterization of a single hydrogen bond in the α-helix of the AAKA(AEAAKA)5AC peptide model and detailed explanation of the mechanism of the α-helix unfolding. The methodology proposed here may be extended to other molecular structures stabilized by internal hydrogen bonds.


Asunto(s)
Química/métodos , Enlaces de Hidrógeno , Modelos Químicos , Péptidos/química , Simulación por Computador , Estructura Secundaria de Proteína , Análisis Espectral
20.
J Agric Food Chem ; 68(2): 541-548, 2020 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-31860295

RESUMEN

Besides their nutritional value, whey protein (WP) peptides are food components retaining important pharmacological properties for controlling hypertension. We herein report how the use of complementary experimental and theoretical investigations allowed the identification of novel angiotensin converting enzyme inhibitory (ACEI) peptides obtained from a WP hydrolysate and addressed the rational design of even shorter sequences based on molecular pruning. Thus, after bromelain digestion followed by a 5 kDa cutoff ultrafiltration, WP hydrolysate with ACEI activity was fractioned by RP-HPLC; 2 out of 23 collected fractions retained ACEI activity and were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). In the face of 128 identified peptides, molecular docking was carried out to prioritize peptides and to rationally guide the design of novel shorter and bioactive sequences. Therefore, 11 peptides, consisting of 3-6 amino acids and with molecular weights in the range from 399 to 674 Da, were rationally designed and then purchased to determine the IC50 value. This approach allowed the identification of two novel peptides: MHI and IAEK with IC50 ACEI values equal to 11.59 and 25.08 µM, respectively. Interestingly, we also confirmed the well-known ACEI IPAVF with an IC50 equal to 9.09 µM. In light of these results, this integrated approach could pave the way for high-throughput screening and identification of new peptides in dairy products. In addition, the herein proposed ACEI peptides could be exploited for novel applications both for food production and pharmaceuticals.


Asunto(s)
Inhibidores de la Enzima Convertidora de Angiotensina/química , Péptidos/química , Proteína de Suero de Leche/química , Animales , Bovinos , Diseño de Drogas , Humanos , Cinética , Simulación del Acoplamiento Molecular , Peso Molecular , Peptidil-Dipeptidasa A/química , Hidrolisados de Proteína/química
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