Effect of heat treatment on structure and immunogenicity of recombinant peanut protein Ara h 2.01

Interactions between protein Z and lycopene: A win-win scenario for both security and stability

Malt protein Z (PZ), the main albumin in malt endosperm, exhibits trypsin inhibitory activity and has the ability to bind fat-soluble active molecules. However, its potential utilization as a food ingredient necessitates an evaluation of its allergenicity. Lycopene has many functional activities, such as antioxidant and treatment or alleviation of various diseases, but its tendency to degrade easily hinders its effective utilization. Therefore, this paper investigates the allergenicity of PZ and provides a win-win scenario that PZ interacts with lycopene. PZ interacts with lycopene through non-covalent interactions with a ratio of 4.07 ± 0.20, leading to the formation of homogenous particles with an increased absolute zeta potential, from -7.3 ± 0.2 to -20.0 ± 0.6. Unsurprisingly, the presence of lycopene alleviates the allergenicity of PZ by decreasing the IgE, mMcp-1 and vascular permeability, such as the plasma mMcp-1 decreased from 245.0 ± 5.2 ng/mL for the PZ group to 217.8 ± 4.1 ng/mL for the PZ-LYC group. To uncover the potential mechanism, the linear antigenic epitopes of PZ by ABCpred were predicted, which are almost the potential binding site of lycopene at PZ. On the other hand, PZ improved the storage stability of lycopene. The addition of PZ increased lycopene retention in solution from 14.9 ± 2.7 % to 65.5 ± 2.8 % over 10 days at room temperature with light exposure. These results provide foundations for PZ utilization concerning security, and give ways to protect bioactive molecules.

Low-pH induced structural changes, allergenicity and in vitro digestibility of lectin from black turtle bean (Phaseolus vulgaris L.)

Lectin was incubated in corresponding acidic buffers (pH 1.0-3.5) for a certain period (0.5, 1, 2, 4, 8, 12 and 24 h) at 25 °C. Low-pH induced changes in structure, allergenicity and in vitro digestibility of lectin from black turtle bean (Phaseolus vulgaris L.) were investigated in the present study. Results indicated that the alteration in structure was a progressive unfolding process mainly depending on pH environment, and the treated lectin attained a stable state at 8 h. Electrophoretic, dynamic light scattering (DLS) and size exclusion chromatography (SEC) analyses suggested that lectin monomers appeared in the solutions of pH < 2.0. Differential scanning calorimetry (DSC) confirmed that thermal stability of lectin weakened in low pH environments. Furthermore, ELISA and in vitro digestion assay showed allergenicity and digestibility significantly decreased with the structural alterations. These results showed low-pH treatments have great potential to reduce the damage of legumes protein consumption.

Trypsin inhibition by Ligupurpuroside B as studied using spectroscopic, CD, and molecular docking techniques

It is well known that Ligupurpuroside B is a water-soluble polyphenolic compound and used to brew bitter tea with antioxidant activities. It acted as a stimulant to the central nervous system and a diuretic (increase the excretion of urine), was used to treat painful throat and high blood pressure, and also exerted weight-loss function. In this regard, a detailed investigation on the mechanism of interaction between Ligupurpuroside B and trypsin could be of great interest to know the pharmacokinetic behavior of Ligupurpuroside B and for the design of new analogues with effective pharmacological properties. Ligupurpuroside B successfully quenched the intrinsic fluorescence of trypsin via static quenching mechanism. The binding constants (K_a) at three temperatures (288, 298, and 308 K) were 1.7841 × 10⁴, 1.6251 × 10⁴ and 1.5483 × 10⁴ L mol^-1, respectively. Binding constants revealed the stronger binding interaction between Ligupurpuroside B and trypsin. The number of binding sites approximated to one, indicating a single class of binding for Ligupurpuroside B in trypsin. The enzyme activity result suggested that Ligupurpuroside B can inhibit trypsin activity. Thermodynamic results revealed that both hydrogen bonds and hydrophobic interactions play main roles in stabilization of Ligupurpuroside B-trypsin complex. Circular dichroism (CD) results showed that the conformation of trypsin changed after bound to ligupurpuroside B. Molecular docking indicated that Ligupurpuroside B can enter the hydrophobic cavity of trypsin and was located near Trp215 and Tyr228 of trypsin. Communicated by Ramaswamy H. Sarma.

Effects of the Varietal Diversity and the Thermal Treatment on the Protein Profile of Peanuts and Hazelnuts

Several buffer compositions were compared for their efficiency in protein extraction from both raw and roasted peanut and hazelnut samples, the final goal being to understand the modification of protein solubility upon roasting and maximize the extraction yield. Denaturant conditions provided by urea-TBS buffer resulted in satisfactory extraction yields for both peanut and hazelnut samples, before and after the thermal treatment. In addition, different varieties of peanuts and hazelnuts were characterized to highlight the extent of variability in the protein profile accounted by the varietal factor and eventual differential resistance among cultivars to protein modification induced by the thermal processing. The protein profile was characterized by gel electrophoresis, and specific bands were analyzed by micro-HPLC-MS/MS coupled to software-based protein identification. No significant difference was observed for the investigated hazelnut cultivars, namely, Campana, Romana, and Georgia, whereas interesting features were presented for the peanut varieties Virginia, Zambia, and China. In particular, Zambia variety lacked two bands of approximately 36 and 24 kDa that were visible in Virginia and China varieties, which could suggest a lower allergenic potential of this particular variety which deserves to be further investigated before drawing final conclusions.