Improvement of Functional Properties of Bovine Serum Albumin through Phosphorylation by Dry-Heating in the Presence of Pyrophosphate

Quantitative Comparative Integrated Proteomic and Phosphoproteomic Analysis of Chicken Egg Yolk Proteins under Diverse Storage Temperatures

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.

Phosphorylated Zein as Biodegradable and Aqueous Nanocarriers for Pesticides with Sustained-Release and anti-UV Properties

Zein's prevalent hydrophobic character is one of the major challenges associated with ineffective utilization as an aqueous nanocarrier for pesticides. Herein, we report an effective approach to hydrophilic modification of zein by phosphorylation using nontoxic sodium tripolyphosphate (STP), thereby improving the water-solubility, foliage wettability, and adhesion ability of zein as a nanocarrier for sustained release of pesticides. The procedure relied on zein grafted with STP via N- and O- phosphate bonds and encapsulation of avermectin (AVM) as a hydrophobic model drug using phosphorylated zein (P-Zein), which achieved pH sensitivity to controlled release of AVM in various applicable environments. The chemical interaction between zein and STP was confirmed by Fourier transform infrared, thermogravimetric analysis, and differential scanning calorimetric. Scanning electron microscopy, dynamic light scattering, and zeta potential technique were applied to investigate their structural characteristics and stability, from which it was found that AVM encapsulated in P-Zein (AVM@P-Zein) formed uniform nanoparticles with average sizes in the range of 174-278 nm under different conditions, and had an excellent stability in aqueous solution. Besides, AVM@P-Zein facilitated the wettability on the foliage surface evidenced from contact angle values owing to the amphiphilic character after phosphorylation as well as enhanced the adhesion ability between liquid and leaf, restricting the pesticide runoff. Ultraviolet-visible spectroscopy was employed to explore the anti-UV property and encapsulation as well as release behavior, which revealed that the presence of P-Zein like a shell protects AVM from UV photolysis with encapsulation efficiency of approximately 81.52%, and the release of AVM from P-Zein showed pH-responsive behavior ascribed to protonation and deprotonation of phosphate under various pH conditions fitting to Elovich kinetic model, achieving the relatively more rapid release under acidic conditions. More importantly, AVM@P-Zein retained the toxicity for insecticidal effect.

Formation mechanism and biological activity of novel thiolated human-like collagen iron complex

To develop an iron supplement that is effectively absorbed and utilized, thiolated human-like collagen was created to improve the iron binding capacity of human-like collagen. A thiolated human-like collagen-iron complex was prepared in a phosphate buffer, and one mole of thiolated human-like collagen-iron possessed approximately 28.83 moles of iron. The characteristics of thiolated human-like collagen-iron were investigated by ultraviolet-visible absorption spectroscopy, Fourier transform infrared spectroscopy, circular dichroism, and differential scanning calorimetry. The results showed that the thiolated human-like collagen-iron complex retained the secondary structure of human-like collagen and had greater thermodynamic stability than human-like collagen, although interactions between iron ions and human-like collagen occurred during the formation of the complex. In addition, to evaluate the bioavailability of thiolated human-like collagen-iron, an in vitro Caco-2 cell model and an in vivo iron deficiency anemia mouse model were employed. The data demonstrated that the thiolated human-like collagen-iron complex exhibited greater bioavailability and was more easily utilized than FeSO4, ferric ammonium citrate, or ferrous glycinate. These results indicated that the thiolated human-like collagen-iron complex is a potential iron supplement in the biomedical field.

Attenuation of allergic immune response phenotype by mannosylated egg white in orally induced allergy in BALB/c mice

Food allergies are attributed to an imbalance in immune response to ubiquitous antigens. A previous study demonstrated that mannose glycation (mannosylation) of ovalbumin decreased allergenicity in vivo. The proposed research targets mannosylation of various common allergens that may help prevent food allergy. Balb/c mice (n = 8) were sensitized toxin egg white, peanut, and whey and treated with mannosylated forms of the test antigens. Glucosylated peanut and cholera toxins were used as controls. Allergic status was assessed as clinical signs, serum histamine, mouse mast cell protease (MMCP), antibody activity, cytokines, and T regulatory cells (T-regs). Significant preventative effects were observed with mannosylated egg white treatment such as reduced clinical signs, histamine, MMCP, specific G, G1, and E antibody activities, and IL-4 and increased IL-10 and CD25(+) Foxp3(+) cells. Other groups did not differ significantly. It was concluded that mannosylated egg white provides a powerful tool to prevent allergic phenotypes with possible relevance to control human egg allergy.

A novel thiolated human-like collage zinc complex as a promising zinc supplement: physicochemical characteristics and biocompatibility

To improve zinc binding ability to human-like collagen (HLC) and stability of metal complex, HLC was thiolated by mercaptosuccinylation reaction with S-acetylmercaptosuccinic anhydride (S-AMSA) at pH8.0. One mole of thiolated HLC-Zn (SHLC-Zn) complex possessed 24.3mol zinc ions when pH was 8.0 and zinc concentration was 15 mM. The physicochemical properties and biocompatibility of thiolated HLC-Zn (SHLC-Zn) complex were investigated by UV-vis, CD, electrophoresis analysis, differential scanning calorimetry (DSC) and cell viability assay, respectively. The results showed that SHLC-Zn complex(1) exhibited higher zinc ions than that of native HLC and still maintained the secondary structure of HLC though interaction occurred between SHLC and zinc ions, (2) increased the apparent molecular weight when compared with native HLC, (3) exhibited greater thermal stability than native HLC, and (4) presented toxicity free for BHK cells. This study suggests that the SHLC-Zn complex is a potential nutrition as well as zinc supplement in the medical application.

Formation and characterization of iron-binding phosphorylated human-like collagen as a potential iron supplement

Iron incorporated into food can induce precipitation and unwanted interaction with other components in food. Iron-binding proteins represent a possibility to avoid these problems and other side effects, as the iron is protected. However, there are several technical problems associated with protein-iron complex formation. In this paper, the iron-binding phosphorylated human-like collagen (Fe-G6P-HLC) was prepared under physiological conditions through phosphorylated modification. One molecule of Fe-G6P-HLC possesses about 24 atoms of Fe. Spectroscopy analysis, differential scanning calorimetry (DSC) and equilibrium dialysis techniques were employed to investigate the characteristics of the Fe-G6P-HLC. The binding sites (nb) and apparent association constant (Kapp) between iron and phosphorylated HLC were measured at nb=23.7 and log Kapp=4.57, respectively. The amount of iron (Fe(2+) sulfate) binding to phosphorylated HLC was found to be a function of pH and phosphate content. In addition, the solubility and thermal stability of HLC were not significantly affected. The results should facilitate the utilization of HLC as a bioactive iron supplement in the food and medical industry and provide an important theoretical evidence for the application of HLC chelates.

Preparation of phosphorylated starch by dry-heating in the presence of pyrophosphate and its calcium-phosphate solubilizing ability

Starch was phosphorylated through dry-heating in the presence of pyrophosphate at various conditions, and the characteristics of phosphorylated starch (PS) were examined. Starch phosphorylation increases as the pH increases from 3 to 6, but diminishes at pH 7. Increased temperatures enhance phosphorylation. Data from (31)P NMR suggests that starch phosphorylation occurs mainly at the C3-OH and C6-OH of the glucose residue. The phosphate linkage is mainly due to monostarch monophosphate. Although starch had almost no calcium phosphate-solubilising capacity, this capacity was markedly enhanced by phosphorylation. X-ray diffraction analysis indicates that the crystal structure of hydroxyapatite was not present in the calcium phosphate-PS complex.

Glycation and phosphorylation of alpha-lactalbumin by dry heating: effect on protein structure and physiological functions

Alpha-lactalbumin (alpha-LA) was glycated with maltopentaose (MP) through the Maillard reaction (MP-alpha-LA) and subsequently phosphorylated by dry heating in the presence of pyrophosphate to investigate its structure and physiological functions. Glycation occurred effectively, and the sugar content of alpha-LA increased by approximately 22.3% through the Maillard reaction. The phosphorylation of MP-alpha-LA was enhanced with an increase in the dry-heating time from 1 to 5 d, and the phosphorous content of MP-alpha-LA increased by approximately 1.01% by dry heating at pH 4.0 and 85 degrees C for 5 d in the presence of pyrophosphate. The electrophoretic mobility of alpha-LA increased with an increase in the phosphorylation level. The circular dichroism spectra showed that the change in the secondary structure of the alpha-LA molecule by glycation and subsequent phosphorylation was slight. However, the Trp fluorescence intensity was increased by phosphorylation after glycation. In addition, the differential scanning calorimetry thermograms of alpha-LA showed that the denaturation temperature of MP-alpha-LA was decreased by phosphorylation. These results indicated that molten (partially unfolded) conformations of alpha-LA were formed by dry heating in the presence of pyrophosphate after glycation. The anti-alpha-LA antibody response was significantly reduced by glycation and subsequent phosphorylation. The suppressive effect of alpha-LA on the production of proinflammatory cytokines such as IL-6 and tumor necrosis factor-alpha from THP-1 cells after stimulation with lipopolysaccharide was significantly enhanced by glycation with MP and was further enhanced by phosphorylation after glycation. The Ca phosphate-solubilizing ability of alpha-LA was enhanced by phosphorylation. The apoptotic activity of alpha-LA was reduced by glycation and subsequent phosphorylation. These results suggest that phosphorylation by dry heating in the presence of pyrophosphate after glycation with MP through the Maillard reaction is a useful method for improvement of the physiological functions of alpha-LA.