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1.
Food Chem ; 304: 125415, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31479995

RESUMO

The aim of our study was to characterize the proteolytic activity of 170 Lactobacillus strains isolated from traditional Mongolian dairy products (yogurt and fermented milk), and to investigate their capacity to generate bioactive peptides during milk fermentation. All isolates were screened for proteolytic activity using skim milk agar-well diffusion test. Fifteen strains (9 Lactobacillus helveticus and 6 Lactobacillus delbrueckii subsp. bulgaricus) were then selected and further evaluated using an original strategy based on multiparametric analysis, taking into account growth rate, acidification capacity, proteolytic activity, cell envelope associated peptidase (CEP) profile and LC-MS/MS analysis of peptides. All parameters were analyzed using principal component analysis (PCA). Results showed that strain growth and acidification correlate with peptide production and that Mongolian L. helveticus strains differ from Western strains in terms of CEP distribution. The PCA revealed that CEP profiles are major determinants of ß-casein hydrolysis patterns. Strains with distinctive proteolytic activities were identified.

2.
Food Chem ; 304: 125448, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31491713

RESUMO

Blood, from slaughterhouses, is an inevitable part of meat production, causing environmental problems due to the large volumes recovered and its low valorization. However, the α137-141 peptide, a natural antimicrobial peptide, can be obtained after hydrolysis of hemoglobin, the main constituent of blood red part. To recover it at a sufficient concentration for antimicrobial applications, a new sustainable technology, called electrodialysis with ultrafiltration membrane (EDUF), was investigated. The α137-141 concentration was increased about 4-fold at a feed peptide concentration of 8% with an enrichment factor above 24-fold. This feed peptide concentration also needed the lowest relative energy consumption. Moreover, this peptide fraction protected meat against microbial growth, as well as rancidity, during 14 days under refrigeration. This peptide fraction was validated as a natural preservative and substitute for synthetic additives against food spoilage. Finally, producing antimicrobial/antioxidant peptide from wastes by EDUF fits perfectly with the concept of circular economy.

3.
Bioresour Technol ; 293: 122090, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31499329

RESUMO

Biofilm bioreactors have already been proven to be efficient systems for microbial lipopeptide production since they avoid foam formation. However, the cell adhesion capacities of the laboratory strain B.subtilis 168 to the biofilm bioreactor support are limited. In this work, we present a novel approach for increasing cell adhesion through the generation of filamentous and/or exopolysaccharide producing B.subtilis 168 mutants by genetic engineering. The single cell growth behavior was analyzed using time-lapse microscopy and the colonization capacities were investigated under continuous flow conditions in a drip-flow reactor. Cell adhesion could be increased three times through filamentous growth in lipopeptide producing B. subtilis 168 derivatives strains. Further restored exopolysaccharide production increased up to 50 times the cell adhesion capacities. Enhanced cell immobilization resulted in 10 times increased surfactin production. These findings will be of particular interest regarding the design of more efficient microbial cell factories for biofilm cultivation.


Assuntos
Bacillus subtilis , Lipopeptídeos , Biofilmes , Reatores Biológicos , Peptídeos Cíclicos
4.
Biodegradation ; 2018 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-30390188

RESUMO

Pseudomonas strains isolated from oil contaminated soils were screened for biosurfactant production. Three out of eleven Pseudomonas isolates were selected for their high emulsifying activity (E24 value on n-hexadecane ~ 78%). These isolates (E39, E311 and E313) were identified as members of the P. putida group using phenotypical methods and a molecular approach. To identify the chemical nature of produced biosurfactants, thin layer chromatography and MALDI-ToF mass spectrometry analysis were carried out and revealed lipopeptides belonging to the syringafactin family. The activity of the produced biosurfactants was stable over a pH range of 6-12, at high salinity (10%) and after heating at 80 °C. Tests in contaminated sand micro-bioreactors showed that the three strains were able to degrade diesel. These results suggest the potential of these syringafactin producing strains for application in hydrocarbon bioremediation.

5.
Front Microbiol ; 9: 2354, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30386307

RESUMO

To compensate for their amino acid auxotrophy, lactobacilli have developed the ability to hydrolyze proteins present in their environment. This proteolytic activity not only generates the free amino acids needed by the bacteria, but also a large variety of peptides, some of which are endowed with biological activities. These so-called "bioactive peptides" (BAPs) are interesting from a nutrition and healthcare perspective. The use of lactic acid bacteria (LAB) such as lactobacilli is an effective strategy for production and valorization of new BAPs. The proteolytic activity of lactobacilli is exerted in a strain- and species-dependent manner: each species exhibits different proteinase content, leading to a large variety of proteolytic activities. This underlines the high potential of Lactobacillus strains to produce novel hydrolysates and BAPs of major interest. This review aims at discussing the potential of different Lactobacillus species to release BAPs from fermentation media and processes. Strategies used for peptide production are presented. Additionally, we propose a methodology to select the most promising Lactobacillus strains as sources of BAPs. This methodology combines conventional approaches and in silico analyses.

6.
Artigo em Inglês | MEDLINE | ID: mdl-29692758

RESUMO

A qualitative study is presented, where the main question was whether food-derived hemorphins, i.e., originating from digested alimentary hemoglobin, could pass the intestinal barrier and/or the blood-brain barrier (BBB). Once absorbed, hemorphins are opioid receptor (OR) ligands that may interact with peripheral and central OR and have effects on food intake and energy balance regulation. LLVV-YPWT (LLVV-H4), LVV-H4, VV-H4, VV-YPWTQRF (VV-H7), and VV-H7 hemorphins that were previously identified in the 120 min digest resulting from the simulated gastrointestinal digestion of hemoglobin have been synthesized to be tested in in vitro models of passage of IB and BBB. LC-MS/MS analyses yielded that all hemorphins, except the LLVV-H4 sequence, were able to cross intact the human intestinal epithelium model with Caco-2 cells within 5-60 min when applied at 5 mM. Moreover, all hemorphins crossed intact the human BBB model with brain-like endothelial cells (BLEC) within 30 min when applied at 100 µM. Fragments of these hemorphins were also detected, especially the YPWT common tetrapeptide that retains OR-binding capacity. A cAMP assay performed in Caco-2 cells indicates that tested hemorphins behave as OR agonists in these cells by reducing cAMP production. We further provide preliminary results regarding the effects of hemorphins on tight junction proteins, specifically here the claudin-4 that is involved in paracellular permeability. All hemorphins at 100 µM, except the LLVV-H4 peptide, significantly decreased claudin-4 mRNA levels in the Caco-2 intestinal model. This in vitro study is a first step toward demonstrating food-derived hemorphins bioavailability which is in line with the growing body of evidence supporting physiological functions for food-derived peptides.

7.
Microb Pathog ; 115: 41-49, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29221796

RESUMO

In this work we evaluated the mode of action of six new synthesized peptides (Met-Asp-Asn; Glu-leu-Ala-Ala-Ala-Cys; Leu-Arg-Asp-Asp-Phe; Gly-Asn-Ala-Pro-Gly-Ala-Val-Ala; Ala-Leu-Arg-Met-Ser-Gly and Arg-Asp-Arg-Phe-Leu), previously identified, from the most active peptide fractions of RuBisCO peptic hydrolysate against Listeria innocua via a membrane damage mechanism. Antibacterial effect and the minimum inhibitory concentrations (MIC) of these peptides were evaluated against six strains and their hemolytic activities towards bovine erythrocytes were determined. Prediction of the secondary structure of peptides indicated that these new antibacterial peptides are characterized by a short peptide chains (3-8 amino acid) and a random coli structure. Moreover, it was observed that one key characteristic of antibacterial peptides is the presence of specific amino acids such as cysteine, glycine, arginine and aspartic acid. In addition the determination of the extracellular potassium concentration revealed that treatment with pure RuBisCO peptides could cause morphological changes of L. innocua and destruction of the cell integrity via irreversible membrane damage. The results could provide information for investigating the antibacterial model of antibacterial peptides derived from RuBisCO protein hydrolysates.


Assuntos
Antibacterianos/síntese química , Antibacterianos/farmacologia , Permeabilidade da Membrana Celular/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Listeria/efeitos dos fármacos , Medicago sativa/química , Peptídeos/farmacologia , Hidrolisados de Proteína/metabolismo , Ribulose-Bifosfato Carboxilase/farmacologia , Sequência de Aminoácidos , Aminoácidos , Animais , Bovinos , Eritrócitos/efeitos dos fármacos , Glucose , Testes de Sensibilidade Microbiana , Modelos Moleculares , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/farmacologia , Peptídeos/síntese química , Conformação Proteica
8.
J Colloid Interface Sci ; 508: 488-499, 2017 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-28865343

RESUMO

Polypeptide/solid charged surface interactions are omnipresent in the biomedical and biochemical fields. The present study aimed to understand the adsorption mechanisms of a cation-exchange membrane (CEM) by a well-characterized peptide mixture at three different pH values. Results demonstrated that fouling was important at pH 6, twice lower at pH 2 and negligible at pH 10. At pH 6, ALPMHIR and TKIPAVFK sequences firstly established electrostatic interactions with the negative CEM charges (SO3-) through their positive K and R residues (NH3+) creating a first nanolayer. Secondly, peptide/peptide interactions occurred through their respective hydrophobic residues creating a second nanolayer. At pH 2, VLVLDTDYK and IDALNENK sequences interacted only electrostatically and that in a lower proportion since at acidic pH values, most of the CEM charges would be protonated and uncharged (HSO3) and then limit the potential electrostatic interactions. In addition, the sequences of peptides interacting at pH 2 and 6 were different. This was explained by their structure in terms of residue nature and position in the sequence. At pH 10, no fouling was observed due to the lack of positive peptide charges. To the best of our knowledge, it is the first in-depth study concerning the fouling of CEMs by peptides from a complex mixture.

9.
Biotechnol J ; 12(7)2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28636078

RESUMO

Lipopeoptides are amphiphilic compounds combining interesting physicochemical properties and biological activities. Due to their high foaming capacity in aerated bioreactor, the development of scalable bioprocesses for their production is a major bottleneck. In addition, the genes involved in the biosynthesis of these lipopeptides are mainly regulated by the quorum sensing, a global regulatory mechanism depending on cell density and known to be activated in biofilms. Several approaches have thus been considered in literature taking into account two criteria, on one side, to favor, control or avoid foam formation and on the other side, to use planktonic or immobilized (biofilm) cells. These different bioprocesses are discussed in the present review along with the purification strategies proposed for extracting and concentrating these biosurfactants.


Assuntos
Bacillus/crescimento & desenvolvimento , Reatores Biológicos/microbiologia , Lipopeptídeos/metabolismo , Bacillus/metabolismo , Biofilmes/crescimento & desenvolvimento , Células Imobilizadas/fisiologia , Fermentação , Percepção de Quorum
10.
Artigo em Inglês | MEDLINE | ID: mdl-28484425

RESUMO

The gut plays a central role in energy homeostasis. Food intake regulation strongly relies on the gut-brain axis, and numerous studies have pointed out the significant role played by gut hormones released from enteroendocrine cells. It is well known that digestive products of dietary protein possess a high satiating effect compared to carbohydrates and fat. Nevertheless, the processes occurring in the gut during protein digestion involved in the short-term regulation of food intake are still not totally unraveled. This review provides a concise overview of the current data concerning the implication of food-derived peptides in the peripheral regulation of food intake with a focus on the gut hormones cholecystokinin and glucagon-like peptide 1 regulation and the relationship with some aspects of glucose homeostasis.

11.
Food Res Int ; 92: 113-118, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-28290288

RESUMO

Dietary proteins have recently been investigated as a new source of DPP-IV inhibitory peptides with limited side effects and promising applications. Numerous studies have highlighted and identified peptide sequences able to inhibit DPP-IV activity in vitro, mostly from milk proteins. However, the correlation to in vivo studies remains scarce because standard in vitro assays with purified enzyme do not accurately simulate key factors impacting peptide bioactivity such as intestinal and brush border enzymes or cellular permeability. Therefore, a DPP-IV activity inhibition assay is here proposed using non differentiated confluent Caco-2 cells to rapidly assess food-derived peptide inhibitory potential in approaching intestinal conditions. DPP-IV gene expression was first checked and specific DPP-IV substrate was used to implement the assay. Using a specific DPP-IV inhibitor confirmed that non differentiated Caco-2 cells express measurable DPPIV activity. This in situ assay was then applied to digests which already demonstrated a DPP-IV inhibitory potential with a standard assay using purified enzyme. Bovine hemoglobin and cuttlefish hydrolysate digests from simulated gastrointestinal digestion exerted a dose response inhibition on DPP-IV activity but displayed different inhibitory potentials.

12.
Bioprocess Biosyst Eng ; 40(2): 161-180, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27738757

RESUMO

Innovations in novel enzyme discoveries impact upon a wide range of industries for which biocatalysis and biotransformations represent a great challenge, i.e., food industry, polymers and chemical industry. Key tools and technologies, such as bioinformatics tools to guide mutant library design, molecular biology tools to create mutants library, microfluidics/microplates, parallel miniscale bioreactors and mass spectrometry technologies to create high-throughput screening methods and experimental design tools for screening and optimization, allow to evolve the discovery, development and implementation of enzymes and whole cells in (bio)processes. These technological innovations are also accompanied by the development and implementation of clean and sustainable integrated processes to meet the growing needs of chemical, pharmaceutical, environmental and biorefinery industries. This review gives an overview of the benefits of high-throughput screening approach from the discovery and engineering of biocatalysts to cell culture for optimizing their production in integrated processes and their extraction/purification.


Assuntos
Enzimas/biossíntese , Enzimas/química , Enzimas/genética , Engenharia de Proteínas/métodos , Catálise
13.
Microb Cell Fact ; 15(1): 147, 2016 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-27553851

RESUMO

BACKGROUND: Because the model yeast Yarrowia lipolytica can synthesize and store lipids in quantities up to 20 % of its dry weight, it is a promising microorganism for oil production at an industrial scale. Typically, optimization of the lipid production process is performed in the laboratory and later scaled up for industrial production. However, the scale-up process can be complicated by genetic modifications that are optimized for one set of growing conditions can confer a less-than-optimal phenotype in a different environment. To address this issue, small cultivation systems have been developed that mimic the conditions in benchtop bioreactors. In this work, we used one such microbioreactor system, the BioLector, to develop high-throughput fermentation procedures that optimize growth and lipid accumulation in Y. lipolytica. Using this system, we were able to monitor lipid and biomass production in real time throughout the culture duration. RESULTS: The BioLector can monitor the growth of Y. lipolytica in real time by evaluating scattered light; this produced accurate measurements until cultures reached an equivalent of OD600nm = 115 and a cell dry weight of 100 g L(-1). In addition, a lipid-specific fluorescent probe was applied which reliably monitored lipid production up to a concentration of 12 g L(-1). Through screening various growing conditions, we determined that a carbon/nitrogen ratio of 35 was the most efficient for lipid production. Further screening showed that ammonium chloride and glycerol were the most valuable nitrogen and carbon sources, respectively, for growth and lipid production. Moreover, a carbon concentration above 1 M appeared to impair growth and lipid accumulation. Finally, we used these optimized conditions to screen engineered strains of Y. lipolytica with high lipid-accumulation capability. The growth and lipid content of the strains cultivated in the BioLector were compared to those grown in benchtop bioreactors. CONCLUSION: To our knowledge, this is the first time that the BioLector has been used to track lipid production in real time and to monitor the growth of Y. lipolytica. The present study also showed the efficacy of the BioLector in screening growing conditions and engineered strains prior to scale-up. The method described here could be applied to other oleaginous microorganisms.


Assuntos
Biomassa , Fermentação , Lipídeos/biossíntese , Yarrowia/metabolismo , Cloreto de Amônio/metabolismo , Reatores Biológicos , Glicerol/metabolismo , Ensaios de Triagem em Larga Escala , Metabolismo dos Lipídeos , Fatores de Tempo , Yarrowia/crescimento & desenvolvimento
14.
Bioresour Technol ; 218: 944-52, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27447921

RESUMO

Culture medium elements were analysed by a screening DoE to identify their influence in surfactin specific production by a surfactin constitutive overproducing Bacillus subtilis strain. Statistics pointed the major enhancement caused by high glutamic acid concentrations, as well as a minor positive influence of tryptophan and glucose. Successively, a central composite design was performed in microplate bioreactors using a BioLector®, in which variations of these impressive parameters, glucose, glutamic acid and tryptophan concentrations were selected for optimization of product-biomass yield (YP/X). Results were exploited in combination with a RSM. In absolute terms, experiments attained an YP/X 3.28-fold higher than those obtained in Landy medium, a usual culture medium used for lipopeptide production by B. subtilis. Therefore, two medium compositions for enhancing biomass and surfactin specific production were proposed and tested in continuous regime in a bubbleless membrane bioreactor. An YP/X increase of 2.26-fold was observed in bioreactor scale.


Assuntos
Bacillus subtilis , Reatores Biológicos/microbiologia , Lipopeptídeos/química , Peptídeos Cíclicos/química , Bacillus subtilis/metabolismo , Biomassa , Meios de Cultura/química
15.
Food Chem ; 211: 306-13, 2016 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-27283637

RESUMO

Bovine cruor, a slaughterhouse by-product, contains mainly hemoglobin, broadly described as a rich source of antimicrobial peptides. In the current context of food safety, bioactive peptides could be of interest as preservatives in the distribution of food products. The aim of this work was to study the α137-141 fragment of hemoglobin (Thr-Ser-Lys-Tyr-Arg), a small (653Da) and hydrophilic antimicrobial peptide. Its production was fast, with more 65% finally produced at 24h already produced after 30min of hydrolysis with pepsin. Moreover, increasing substrate concentration (from 1 to 8% (w/v)) resulted in a proportional augmentation of α137-141 production (to 807.95±41.03mgL(-1)). The α137-141 application on meat as preservative (0.5%, w/w) reduced the lipid oxidation about 60% to delay meat rancidity. The α137-141 peptide also inhibited the microbial growths under refrigeration during 14days. These antimicrobial effects were close to those of the butylated hydroxytoluene (BHT).


Assuntos
Matadouros , Peptídeos Catiônicos Antimicrobianos/análise , Conservantes de Alimentos/análise , Carne/análise , Carne/microbiologia , Animais , Anti-Infecciosos/análise , Bovinos , Refrigeração
16.
Ultrason Sonochem ; 32: 137-146, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27150754

RESUMO

Ultrasound-assisted extraction (UAE) of antioxidant polyphenols from chicory grounds was studied in order to propose a suitable valorization of this food industry by-product. The main parameters influencing the extraction process were identified. A new mathematical model for multi-criteria optimization of UAE was proposed. This kinetic model permitted the following and the prediction of the yield of extracted polyphenols, the antioxidant activity of the obtained extracts and the energy consumption during the extraction process in wide ranges of temperature (20-60°C), ethanol content in the solvent (0-60% (vol.) in ethanol-water mixtures) and ultrasound power (0-100W). After experimental validation of the model, several simulations at different technological restrictions were performed to illustrate the potentiality of the model to find the optimal conditions for obtaining a given yield within minimal process duration or with minimal energy consumption. The advantage of ultrasound assistance was clearly demonstrated both for the reduction of extraction duration and for the reduction of energy consumption.


Assuntos
Antioxidantes , Polifenóis/química , Ultrassom , Etanol , Cinética , Extratos Vegetais
17.
Electrophoresis ; 37(13): 1814-22, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-26990205

RESUMO

Consumers and governments have become aware how the daily diet may affect the human health. All proteins from both plant and animal origins are potential sources of a wide range of bioactive peptides and the large majority of those display health-promoting effects. In the meat production food chain, the slaughterhouse blood is an inevitable co-product and, today, the blood proteins remain underexploited despite their bioactive potentiality. Through a comparative food peptidomics approach we illustrate the impact of resolving power, accuracy, sensitivity, and acquisition speed of low-resolution (LR)- and high-resolution (HR)-LC-ESI-MS/MS on the obtained peptide mappings and discuss the limitations of MS-based peptidomics. From in vitro gastrointestinal digestions of partially purified bovine hemoglobin, we have established the peptide maps of each hemoglobin chain. LR technique (normal bore C18 LC-LR-ESI-MS/MS) allows us to identify without ambiguity 75 unique peptides while the HR approach (nano bore C18 LC-HR-ESI-MS/MS) unambiguously identify more than 950 unique peptides (post-translational modifications included). Herein, the food peptidomics approach using the most performant separation methods and mass spectrometers with high-resolution capabilities appears as a promising source of information to assess the health potentiality of proteins.


Assuntos
Cromatografia Líquida/métodos , Digestão , Análise de Alimentos , Hemoglobinas/metabolismo , Peptídeos/metabolismo , Proteômica , Espectrometria de Massas em Tandem/métodos , Animais , Bovinos , Técnicas In Vitro , Mapeamento de Peptídeos
18.
Artigo em Inglês | MEDLINE | ID: mdl-26998857

RESUMO

LVV-h7 (LVVYPWTQFR) is a bioactive peptide that can be obtained from blood as waste of food industry, more precisely from hemoglobin hydrolysis by pepsin. This opioid peptide belongs to the hemorphins family and have strong physiological effects that bring its use in pharmaceutics and various therapeutic treatments attractive, in particular for substituting its costly chemically synthetized analogous. Hemoglobin hydrolysis by pepsin generates a huge variety of peptides among whose LVV-h7 can be purified by liquid-liquid extraction (LLE). Herein, selective preparation of this peptide is proposed by a microfluidic-based continuous reaction-separation process. Hemoglobin hydrolysis in microreactor was firstly coupled to LVV-h7 LLE in octan-1-ol and then coupled to LVV-h7 back LLE in acidic water. This continuous process allowed to prepare pure LVV-h7, as confirmed by liquid chromatography and mass spectrometry. The microfluidic circuit also allowed octan-1-ol recycling in a closed loop, making this method more sustainable than similar biphasic batch process.


Assuntos
Reatores Biológicos , Hemoglobinas/metabolismo , Extração Líquido-Líquido/instrumentação , Técnicas Analíticas Microfluídicas/instrumentação , Pepsina A/metabolismo , Fragmentos de Peptídeos/metabolismo , Animais , Bovinos , Desenho de Equipamento , Reutilização de Equipamento , Hemoglobinas/análise , Hemoglobinas/química , Extração Líquido-Líquido/métodos , Técnicas Analíticas Microfluídicas/métodos , Modelos Biológicos , Pepsina A/química , Fragmentos de Peptídeos/análise , Fragmentos de Peptídeos/química , Proteólise
19.
Food Res Int ; 89(Pt 1): 382-390, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28460928

RESUMO

Dietary proteins have been reported to induce a strong feeling of satiety that has been partially explained by gut hormone level increase. Up to date, various protein hydrolysates have demonstrated in vitro and in vivo their potential to stimulate gut hormone secretion related to food intake decrease and their mechanisms of action have just started to be resolved. In this context, this study aimed at identifying new peptide sequences involved in gut hormone secretion released by protein in vitro gastrointestinal digestion. Targeted gut hormones were Cholecystokinin (CCK) and Glucagon-Like Peptide 1 (GLP-1). The activity of DPP-IV was also considered as it strongly modulates GLP-1 action. In a previous study, simulated digestion of dietary protein has generated hydrolysates with enhancing effect on CCK and GLP-1 secretion in STC-1 cells as well as DPP-IV inhibitory properties. Successive purification steps were performed to isolate peptide fractions involved in these bioactivities whose sequence was determined by LC-MS-MS. Three peptide sequences ANVST, TKAVEH and KAAVT were pointed out for their stimulating effects on GLP-1 secretion. The sequence VAAA was isolated for its DPP-IV inhibitory properties. Two peptide groups were strongly involved in CCK release sharing a certain occurrence of aromatic amino acid residues.

20.
J Agric Food Chem ; 64(3): 663-70, 2016 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-26671070

RESUMO

In shrimp, the development of postmortem melanosis resulting from phenoloxidase activities leads to important economic losses. Phenoloxidase enzymes include catechol oxidases, laccases, and tyrosinases, but hemocyanin is also capable of phenoloxidase activities. These activities have been explored in Penaeus monodon, using different substrates. Results highlighted that tyrosinase-specific substrates were little oxidized, whereas hydroquinone (laccase-specific substrate) was more highly oxidized than l-DOPA (nonspecific substrate) in the pereopods and pleopods. Global phenoloxidase activity, assayed with l-DOPA, did not appear thermally stable over time and probably resulted from phenoloxidase enzymes. Conversely, the laccase-like activity assayed with hydroquinone was thermally stable over time, reflecting the thermal stability of hemocyanin. Independently of the anatomical compartment, the temperature, or the substrate, the highest activities were assayed in the cuticular compartments. This study demonstrates the complexity of phenoloxidase activities in P. monodon, and the importance of considering all the activities, including laccase-like activities such as that of hemocyanin.


Assuntos
Hemocianinas/metabolismo , Lacase/metabolismo , Melaninas/metabolismo , Penaeidae/enzimologia , Animais , Estabilidade Enzimática , Hemocianinas/química , Lacase/química , Melaninas/química , Oxirredução , Penaeidae/metabolismo , Especificidade por Substrato
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