A new method for determination of antithrombotic activity of egg white protein hydrolysate by microplate reader

A new method for the determination of antithrombotic activity of egg white protein hydrolysate （EWPH） was developed using a microplate reader. Reaction was carried out at 37℃and pH 7.2 with fibrinogen concentration 0.1%. Microplate reading was conducted at 405 nm. Inhibition rate of EWPH on thrombin activity showed linearity （R2 = 0.9971）, when the inhibition rate was in the range of 10-90%. The lower limit of detection （LLD, at 99.7% probability） and the biological limit of detection （BLD, at 99.7% probability） of the method were 10.643 and 40 mg/mL, respectively. The repeatability standard deviation （R.S.D.） was 1.08%. The standard deviation of the method was ±0.027 AT-U.

Regulation of Microstructure of Calcium Carbonate Crystals by Egg White Protein

Crystal growth of calcium carbonate in biological simulation was investigated via egg white protein with different volume fractions,during which calcium carbonate was synthesized by calcium chloride and sodium carbonate.The morphology,thermal properties and microstructure of the calcium carbonate micro-to-nanoscale crystals were characterized by scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,Fourier transform infrared spectroscopy（FTIR）,thermogravimetric analysis（TG） and X-ray diffraction（XRD） analysis.The results show that the volume fraction of egg white protein has great influence on the shape,size and morphology of calcium carbonate crystals.The calcium carbonate crystals were the mixtures of calcite-vaterite-like crystals including spherical and rough surface,which are different from that formed in pure water.With the increase of egg white protein concentration,the diameter of calcium carbonate crystals changed,the amount of formed spherical calcium carbonate particles decreased and that of vaterite increased.These results indicate that the coordination and electrostatic interaction between egg white protein and Ca2＋ significantly affect the calcium carbonate crystalization.

Interaction mechanism of egg white-derived ACE inhibitory peptide TNGIIR with ACE and its effect on the expression of ACE and AT1 receptor

The egg white-derived hexapeptide TNGIIR inhibits angiotensin-converting enzyme(ACE)activity in vitro.In this work,molecular docking revealed that TNGIIR established hydrogen bonds with the S1(Ala 354),S2(Gln 281,His 513,Tyr 520 and Lys 511)and S1(Glu 162)pockets of ACE.In addition,the potential antihypertensive effect of the oral administration of TNGIIR in spontaneously hypertensive rats(SHR)was investigated,as was the effect of this peptide on the mRNA expression of ACE and angiotensin type 1(AT1)and type 2(AT2)receptors in renal tissue.The oral administration of TNGIIR(2,10 and 50 mg/kg)for up to four weeks did not reduce the blood pressure of SHR,in contrast to captopril(10 mg/kg,orally),but attenuated the mRNA expression of ACE and AT1 receptor(as did captopril).In contrast,both TNGIIR and captopril enhanced the expression of AT2 receptor mRNA.There was no change in the circulating concentration of angiotensin I,but a slight decrease(about 10%)was seen in the concentration of circulating angiotensin II with TNGIIR and captopril.

Phase Transformation of Amorphous Calcium Carbonate to Single-Crystalline Aragonite with Macroscopic Layered Structure in the Presence of Egg White Protein and Zinc Ion

Highly oriented calcium carbonate lamellas are exquisite structure produced by biomineralization. Strategies mimicking nature have been developed to synthesize inorganic materials with excellent structures and optimal properties. In our strategy, egg white protein and zinc ion were employed in the solution to induce the crystallization of calcium carbonate, resulting in the macroscopic aragonite laminate with an average length of 1.5 mm, which was comprised of single-crystalline tablets. During the crystallization at initial stage, it was found that the particles displayed the characteristics of amorphous calcium carbonate, which was then transformed into the sophisticated structured aragonite through a multistage assembly process. The rebuilt nacre structure in vitro was achieved owing to the synergistic effects of egg white protein and zinc ion.

Liquid Chromatographic Assay of Peptides Activity with Inhibiting Angiotensin Converting Enzyme

A rapid, simple and interference-free method was developed to evaluate the inhibitory activity of hydrolyzed peptides from egg white protein against the angiotensin-converting enzyme. The total reaction volume was 60 μL, saving the cost. The assay was based on a HPLC separation and quantification of the synthetic substrate hippuryl-L-histidyl-L-leucine and its hydrolyzed product-hippuric acid; the separation was performed on a C18 column eluted by a mobile phase of acetonitrile/water（0.5% TFA） at a volume ratio of 25：75. At a signal to noise ratio（S/N） of 10, the detective limit of the quantitation of hippuric acid was （0.4600±0.0097） μmol/L. The standard curve shows a linear response with a slope of 49488 and a correlation coefficient of 0.9995. The assay was adequate for the study of ACE inhibition by Captopril and peptides derived from food protein, and showed a very good correlation with the previous methods.

Aspergillus oryzae reduces IgE binding ability of allergenic egg white proteins

Egg white proteins are one of the major allergens. The objective of this study was to investigate the effect of Aspergillus oryzae cultivation on IgE binding ability of egg white proteins. Effect of A. oryzae on egg white proteins was determined using ninhydrin method,SDS-PAGE, ELISA, fluorescence FITC labeling, MALDITOF-MS and LC-MS/MS analysis. Adding mycelium of A. oryzae ATCC 1011 and 16868 substantially reduced the IgE binding ability of acidified egg white after 24 h incubation. The binding capacity of egg white proteins to IgE in plasma from four egg allergy patients was almost completely lost after incubation with mycelium of ATCC16868. Results from SDS-PAGE, free amino acid analysis,MALDI-TOF-MS and LC-MS/MS indicated that there was no substantial protein degradation during incubation.Therefore, the reduction of IgE binding ability of egg white proteins during A. oryzae treatment was probably due to a loss of ～1700 Da mass including a fragment of the ovomucoid N terminus.

An endoparasitoid uses its egg surface proteins to regulate its host immune response

With proteomic analysis,we identified 379 egg surface proteins from an endoparasitoid,Cotesia chilonis.Proteins containing conserved enzymatic domains constitute a large proportion of egg surface components.Some proteins,such as superoxidase dismutase,homolog of C.rubecula 32-kDa protein,and immunoevasive protein-2A,are classical parasitism factors that have known functions in host immunity regulation.Melanization assays revealed that a novel egg surface protein,C.chilonis egg surface serpin domain-containing protein had the same function as a C.chilonis venom serpin,as both suppressed host melanization in a dose-dependent manner.C.chilonis egg surface serpin domain-containing protein is mainly transcribed in C.chilonis oocytes with follicular cells,and it is located on both the anterior and posterior sides of the mature egg surface.Additionally,we used LC-MS/MS to identify 586 binding proteins sourced from C.suppressalis plasma located on the eggshell surface of C.chilonis,which included some immunity-related proteins.These results not only indicate that C.chilonis uses its egg surface proteins to reduce the immune response of its host but also imply that endoparasitoid egg surface proteins might be a new parasitism factor involved in host immune regulation.

Effects of freeze-drying and spray drying processes on functional properties of phosphorylation of egg white protein

Egg white protein(EWP)was phosphorylated with Sodium Tripolyphosphate(STP)at pH 4.5.Freeze drying and spray drying were used for drying purpose and the effects of these drying methods on the functional properties were investigated.The functional properties of native and modified proteins were also determined.The results demonstrated that phosphorylation of EWP markedly improved its functional properties,and that it was more effective for the food industry.The freeze-dried STP-EWP powders were superior in terms of solubility,emulsion stability,water holding capacity,oil and water absorption capacity and heat gel strength than spray-dried STP-EWP powders.The results in viscosity showed no significant differences between freeze-dried and spray dried.The spray-dried powders were better in terms of foaming ability and foam stability than freeze-dried powders.However,the spray drying required the longest time to produce.Freeze drying was found to be the best method in terms of production of modified EWP powders with superior functional properties.

Differences in protein composition and functional properties of egg whites from four chicken varieties

Egg white protein(EWP)is widely used in the food industry for its technological properties,which are affected by diet-and breed-related changes in its composition.Therefore,the objective of this study was to analyse the relationship between hen variety and the protein composition,functional characteristics,and physicochemical properties of egg white(EW)obtained from Black Bone(BB),Gushi(GS),Hy-Line(HY-LINE),and Harbin White(HW)chickens.The protein composition of EW was analysed by high performance liquid chromatography(HPLC),while the secondary structure of EWP was assessed by Raman spectroscopy.BB and GS EWs had significantly higher ovalbumin content(183.38 and 168.56μg/mL,respectfully)than HY-LINE and HW EWs(148.15 and 147.44μg/mL,respectfully)(p<0.05).In accordance with the higher ovalbumin content,BB and GS EWs possessed significantly better foaming and gel properties,along with greater sulfhydryl group and disulfide bond content in the EWPs,than HY-LINE and HW EWs(p<0.05).Additionally,the ovotransferrin,ovomucin,and lysozyme contents also differed significantly among EWs from the four varieties(p<0.05).Further,the EWPs possessed significant differences in amino acid(AA)content,including essential AAs,those contributing to egg flavour,and those associated with children’s growth and preterm infant health.In conclusion,differences in protein composition likely led to dissimilar functional and physicochemical properties among EWs obtained from different hen varieties,which could provide a reference for food production and genetic breeding of laying hens.