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Organic & Biomolecular Chemistry Sep 2018Antimicrobial and anti-proliferative meleagrin and oxaline are roquefortine C-derived alkaloids produced by fungi of the genus Penicillium. Tandem O-methylations...
Antimicrobial and anti-proliferative meleagrin and oxaline are roquefortine C-derived alkaloids produced by fungi of the genus Penicillium. Tandem O-methylations complete the biosynthesis of oxaline from glandicoline B through meleagrin. Currently, little is known about the role of these methylation patterns in the bioactivity profile of meleagrin and oxaline. To establish the structural and mechanistic basis of methylation in these pathways, crystal structures were determined for two late-stage methyltransferases in the oxaline and meleagrin gene clusters from Penicillium oxalicum and Penicillium chrysogenum. The homologous enzymes OxaG and RoqN were shown to catalyze penultimate hydroxylamine O-methylation to generate meleagrin in vitro. Crystal structures of these enzymes in the presence of methyl donor S-adenosylmethionine revealed an open active site, which lacks an apparent base indicating that catalysis is driven by proximity effects. OxaC was shown to methylate meleagrin to form oxaline in vitro, the terminal pathway product. Crystal structures of OxaC in a pseudo-Michaelis complex containing sinefungin and meleagrin, and in a product complex containing S-adenosyl-homocysteine and oxaline, reveal key active site residues with His313 serving as a base that is activated by Glu369. These data provide structural insights into the enzymatic methylation of these alkaloids that include a rare hydroxylamine oxygen acceptor, and can be used to guide future efforts towards selective derivatization and structural diversification and establishing the role of methylation in bioactivity.
Topics: Imidazoles; Methyltransferases; Models, Molecular; Ovomucin; Penicillium; Protein Conformation
PubMed: 30141817
DOI: 10.1039/c8ob01565a -
Poultry Science Jan 2019Ovomucin is known to be critical for keeping the high quality and freshness of thick albumen, but there is lack of understanding on the dynamics changes of this...
Ovomucin is known to be critical for keeping the high quality and freshness of thick albumen, but there is lack of understanding on the dynamics changes of this important protein during storage. This study aimed to investigate the relationship between ovomucin content and egg freshness during storage. Firstly, the viscoelasticity of albumen was shown to be much higher than that of ovomucin-depleted albumen from rheological analysis results, indicating that ovomucin is an important component in maintaining the natural viscoelasticity of albumen. Then, the ovomucin content determined by ELISA method was compared to albumen pH, Haugh unit (HU), and yolk index in terms of egg white quality and to the time of storage in terms of egg freshness at 4°C, 25°C, and 37°C, respectively. Results of the transformation kinetic showed a decrease in ovomucin content with prolonged storage time (P ≤ 0.01). Correlation analysis showed a high positive correlation between ovomucin content and HU (P ≤ 0.01) and a high negative correlation between ovomucin content and the albumen pH (P ≤ 0.01) at the test temperatures. We therefore conclude that ovomucin content in albumen can be used as an index for egg freshness. At last, predictive models of the equivalent egg age (4°C and 25°C) for evaluating the egg freshness were established by means of exponential regression model with ovomucin content as the variable. These results can provide a theoretical and technical basis for the storage and fresh evaluation of shell eggs.
Topics: Animals; Chickens; Egg White; Egg Yolk; Eggs; Food Storage; Hydrogen-Ion Concentration; Ovomucin; Temperature; Time Factors; Viscosity
PubMed: 30107537
DOI: 10.3382/ps/pey349 -
International Journal of Biological... Nov 2018Ovomucin (OVM) plays an important role in inhibiting infection of various pathogens. However, this bioactivity mechanism is not much known. Here, the role of sialic acid...
Ovomucin (OVM) plays an important role in inhibiting infection of various pathogens. However, this bioactivity mechanism is not much known. Here, the role of sialic acid in OVM anti-virus activity has been studied by ELISA with lectin or ligand. Structural changes of OVM after removing sialic acid were analyzed by circular dichroism and fluorescence spectroscopy. OVM could be binding to the hemagglutinin (HA) of avian influenza viruses HN and HN, this binding was specific and required the involvement of sialic acid. When sialic acid was removed, the binding was significantly reduced 71.5% and 64.35%, respectively. Therefore, sialic acid was proved as a recognition site which avian influenza virus bound to. Meanwhile, the endogenous fluorescence and surface hydrophobicity of OVM removing sialic acid were increased and the secondary structure tended to shift to random coil. This indicated that OVM molecules were in an unfolded state and spatial conformation disorder raising weakly. Remarkably, free sialic acid strongly promoted OVM binding to HA and thereby enhanced the interaction. It may contribute to the inhibition of host cell infection, agglutinate viruses. This study can be extended to the deepening of passive immunization field.
Topics: Antiviral Agents; Hemagglutinins; Influenza A Virus, H1N1 Subtype; Influenza A Virus, H5N1 Subtype; N-Acetylneuraminic Acid; Ovomucin
PubMed: 30071221
DOI: 10.1016/j.ijbiomac.2018.07.186 -
Korean Journal For Food Science of... Apr 2018To shorten the production cycle of Zaodan, this study first pickled Zaodan by a novel technology - vacuum decompression technology. Vacuum decompression technology could...
To shorten the production cycle of Zaodan, this study first pickled Zaodan by a novel technology - vacuum decompression technology. Vacuum decompression technology could reduce the pickling time of Zaodan from 20 wk to about 9 wk. The protein content, moisture and pH of the Zaodan egg white gradually decreased with a concomitant increase in salt during the pickling process. The total sulfhydryl group (SH) group content of the egg white proteins was increased to 2.43×10 mol/L after being pickled for 30 d, whereas the content of disulphide bonds (SS) was reduced to 23.35×10 mol/L. The surface hydrophobicity was lowest after pickling for 30 d. In addition, great changes occurred in the secondary structure of the egg white proteins after pickling for 20 d. The disappearance of ovomucin was noticeable based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis.
PubMed: 29805279
DOI: 10.5851/kosfa.2018.38.2.291 -
Journal of Animal Science Feb 2018The aim of this study was to investigate how dietary supplementation of tea polyphenols (TP) and tea catechins (TC) affect laying performance, albumen quality, ovomucin...
The aim of this study was to investigate how dietary supplementation of tea polyphenols (TP) and tea catechins (TC) affect laying performance, albumen quality, ovomucin composition, and magnum morphology of laying hens in the late phase of production. Two hundred seventy Hy-Line Brown laying hens (64 wk old) were assigned to a basal diet (the control), the basal diet supplemented with 200 mg/kg tea polyphenols (TP200) or 200 mg/kg tea catechins (TC200). Each treatment had 6 replicates with 15 hens each. The feeding trial lasted 10 wks. Over the course of the trial, dietary supplementation with TP200 significantly increased the egg production (EP) and improved the feed conversion ratio (FCR) in wk 6 to 10 and wk 1 to 10 (P < 0.05). The albumen height and the Haugh unit (HU) of hens fed TP200 were higher than those of hens fed the control diet at wks 8 and 10 (P < 0.05). However, there were no significant differences in the albumen height and the HU between the TP200 and TC200 groups (P > 0.05). The SDS-PAGE analysis indicated that bands of the ovomucin fractions in the TP200 group had the highest intensity compared with those of the control and TC200 groups. Compared with the control, there was a significant increase in protein sulfhydryl (SH) content of the albumen in the TP200 group at the end of experiment, while a significant decrease in protein carbonyl content and protein surface hydrophobicity (P < 0.05). There were also obvious increase in the height and width of the primary folds, epithelial cell height, and cilia height of the simple columnar epithelium in the TP200 group compared with the control and TC200 groups (P < 0.05). In conclusion, dietary supplementation with 200 mg/kg TP can improve performance, albumen quality, and magnum morphology of aged hens. In addition, TP rather than TC could improve the health status of the magnum for aged layers.
Topics: Animal Feed; Animals; Chickens; Diet; Dietary Supplements; Female; Ovum; Polyphenols; Protein Carbonylation; Random Allocation; Tea
PubMed: 29378003
DOI: 10.1093/jas/skx007 -
Poultry Science Apr 2018Egg white contains many functionally important proteins: ovalbumin (54%), ovotransferrin (12%), ovomucoid (11%), ovoglobulin (G2 and G3, 8%), ovomucin (3.5%), and... (Review)
Review
Egg white contains many functionally important proteins: ovalbumin (54%), ovotransferrin (12%), ovomucoid (11%), ovoglobulin (G2 and G3, 8%), ovomucin (3.5%), and lysozyme (3.5%) are major proteins, while ovoinhibitors, ovomacroglobulin, ovoglycoprotein, ovoflavoprotein, thiamine-binding proteins, and avidin are minor proteins present in egg white. These proteins, as well as the peptides derived from the proteins, have been recognized for their functional importance as antioxidant, antimicrobial, metal-chelating, anti-viral, anti-tumour, and angiotensin-converting enzyme (ACE)-inhibitory activities. Among the functional properties of the peptides, antioxidant and antimicrobial activities are important characteristics for food processing while other properties such as ACE-inhibitory activity of the peptides can have important health-related functionalities. Bioactive peptides can be produced from egg white proteins by enzyme hydrolysis, chemical treatments, or thermal treatments at different pH conditions. The effective functional peptides produced from egg white proteins are usually smaller than 2 kDa in molecular size. However, these peptides are known for their beneficial activities in vitro only, and little work has been done to prove their beneficial effects in vivo. Therefore, further studies are needed to see if the bioactive peptides derived from egg white proteins are helpful for humans in the future.
Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Antioxidants; Chickens; Egg Proteins
PubMed: 29340654
DOI: 10.3382/ps/pex399 -
Scientific Reports Jul 2017The major components of vitelline membrane (VM) are ovomucin, VM outer (VMO) I and VMO II. At present, the distribution pattern of maternal cells on the VM has not been...
The major components of vitelline membrane (VM) are ovomucin, VM outer (VMO) I and VMO II. At present, the distribution pattern of maternal cells on the VM has not been described in detail. In this study, the existence and distribution characteristics of maternal cells on VM were observed. There were more than 3.2 × 10 somatic cells on VM, which were uneven distributed. The calcein AM/PI staining of the maternal cells on the VM showed that the cells' viability changed with the freshness of the eggs, and that the maternal cells gradually underwent apoptosis and became degraded. The results of morphology of different tissues indicated that the most of maternal cells on the VM were granulosa cells. Moreover, the karyotype of the cultured granulosa cells, which is the main source of cells on VM, were identified as the normal diploid karyotype of chicken. Furthermore, the VM DNA extracted from chickens and quails, which represent the eggs of different size, was adequate for further genetic analysis. The VM DNA was easily accessible and relatively constant, without cross-contamination. Therefore, the VM DNA could potentially be applied for the molecular traceability between eggs and chickens, and be beneficial in avian ecology research studies.
Topics: Animals; Apoptosis; Cell Survival; Chickens; DNA; Diploidy; Female; Granulosa Cells; Karyotyping; Vitelline Membrane
PubMed: 28747770
DOI: 10.1038/s41598-017-06996-1 -
Journal of Nutritional Science and... 2017We propose a new oral immunotherapy (OIT) method that includes a small amount of a food allergen in the diet. However, it is not clear whether this method will induce...
We propose a new oral immunotherapy (OIT) method that includes a small amount of a food allergen in the diet. However, it is not clear whether this method will induce oral desensitization and immune tolerance. Therefore, we investigated the therapeutic effectiveness using a 1% food allergen diet in an allergic mouse model. C3H/HeJ mice were sensitized to ovomucoid (OM) in alum four times at 12-d intervals. Sensitized mice were divided into two groups: the OIT group (19% casein diet with 1% OM) and the non-treated group (20% casein diet without OM). The non-sensitized mice served as the non-allergy group. The OIT treatment was performed for 4 wk. To assess desensitization and immune tolerance, we performed oral and intraperitoneal OM challenges, assessed vascular permeability of the dorsal skin, and measured allergic biomarkers. The OIT group exhibited significantly lower oral symptom scores and vascular permeability than the non-treated group, but the two groups did not differ in intraperitoneal allergy symptom scores. Furthermore, the OIT group had significantly higher OM-specific IgA levels in their plasma than the non-treated group. However, the plasma levels of OM-specific IgE, IgG1, and IgG2a were not significantly different between the OIT and the non-treated groups. These results suggest that the proposed OIT using an OM-supplemented diet may induce desensitization, but not immune tolerance, in an OM allergic mouse model.
Topics: Administration, Oral; Animals; Biomarkers; Cell Culture Techniques; Desensitization, Immunologic; Diet; Disease Models, Animal; Egg Hypersensitivity; Endpoint Determination; Female; Immunoglobulin E; Immunoglobulin G; Mice; Mice, Inbred C3H; Ovomucin
PubMed: 28552874
DOI: 10.3177/jnsv.63.104 -
Nutrients Feb 2017Gal d 1 (ovomucoid) is the dominant allergen in the chicken egg white. Hypoallergenic variants of this allergen can be used in immunotherapy as an egg allergy treatment...
Gal d 1 (ovomucoid) is the dominant allergen in the chicken egg white. Hypoallergenic variants of this allergen can be used in immunotherapy as an egg allergy treatment approach. We hypothesised that disruption of two of the nine cysteine-cysteine bridges by site-directed mutagenesis will allow the production of a hypoallergenic variant of the protein; Methods: Two cysteine residues at C192 and C210 in domain III of the protein were mutated to alanine using site-directed mutagenesis, to disrupt two separate cysteine-cysteine bridges. The mutated and non-mutated proteins were expressed in () by induction with isopropyl β-d-1-thiogalactopyranoside (IPTG). The expressed proteins were analysed using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting to confirm expression. Immunoglobulin E (IgE) reactivity of the two proteins was analysed, by immunoblotting, against a pool of egg-allergic patients' sera. A pool of non-allergic patients' sera was also used in a separate blot as a negative control; Results: Mutant Gal d 1 showed diminished IgE reactivity in the immunoblot by showing lighter bands when compared to the non-mutated version, although there was more of the mutant protein immobilised on the membrane when compared to the wild-type protein. The non-allergic negative control showed no bands, indicating an absence of non-specific binding of secondary antibody to the proteins; Conclusion: Disruption of two cysteine bridges in domain III of Gal d 1 reduces IgE reactivity. Following downstream laboratory and clinical testing, this mutant protein can be used in immunotherapy to induce tolerance to Gal d 1 and in egg allergy diagnosis.
Topics: Allergens; Animals; Chickens; Cysteine; Egg Hypersensitivity; Egg White; Escherichia coli; Female; Genetic Techniques; Humans; Immune Tolerance; Immunoglobulin E; Immunotherapy; Mutagenesis; Mutation; Ovomucin
PubMed: 28230769
DOI: 10.3390/nu9020171 -
Poultry Science May 2017The aim of this study was to evaluate the effect of different protein ingredients on performance, egg quality, organ health, and jejunum morphology of laying hens. A...
The aim of this study was to evaluate the effect of different protein ingredients on performance, egg quality, organ health, and jejunum morphology of laying hens. A total of 216 32-wk-old Hy-Line W36 laying hens with similar egg production was randomly divided into 3 treatment groups with 6 replicates of 12 birds each. The experimental diets were isocaloric (metabolizable energy, 2 655 kcal/kg) and isonitrogenous (crude protein, 16.5%). The control group was fed a corn-soybean meal basal diet (SBM), and the other 2 experimental diets consisted of a basal diet with 195.0 g/kg low-gossypol cottonseed meal (LCSM) or 292.0 g/kg double-zero rapeseed meal (DRM). The feeding trial lasted 12 weeks. The egg production, daily feed intake, egg weight, and feed conversion ratio were not affected (P > 0.05) by diets used. The daily egg mass was decreased in the LCSM group in wk 7 to 12 (P < 0.05). Albumen height, Haugh unit, albumen weight, albumen proportion, and oviduct index were reduced in the 195.0 g/kg LCSM at wk 12 (P < 0.05), while yolk color was increased (P < 0.05). A lower yolk weight, yolk proportion, abdominal fat, dry matter of the liver, and fat content of the liver were observed in the DRM group at wk 12 (P < 0.05). Using LCSM or DRM as a sole protein ingredient in the diet reduced the ovomucin content of albumen when stored 28 d at 4°C. The villous height of the jejunum in the LCSM group was the lowest among treatments (P < 0.05). The mucosal columnar epithelial cell layer of the magnum in the LCSM group was incomplete, and there was a little albumen secretions in the lumen of the magnum. Together, our results suggest that the 195.0 g/kg LCSM diet may produce an adverse effect on daily egg mass and albumen quality. The adverse effect might be associated with the reduction of absorption ability in the jejunum and secretion capacity in the magnum.
Topics: Amino Acids; Animal Feed; Animal Nutritional Physiological Phenomena; Animals; Brassica rapa; Chickens; Diet; Dietary Proteins; Eggs; Female; Gossypium; Jejunum; Liver; Oviposition
PubMed: 27794543
DOI: 10.3382/ps/pew396