Structure, functional and physicochemical properties of lotus seed protein under different pH environments.

BACKGROUND: The present study investigated the structure, functional and physicochemical properties of lotus seed protein (LSP) under different pH environments. The structures of LSP were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Fourier transform infrared spectroscopy (FTIR), zeta potential, particle size distributions, free sulfhydryl and rheological properties. The functional and physicochemical properties of LSP were characterized by color, foaming property, emulsification property, solubility, oil holding capacity, water holding capacity, differential scanning calorimetry analysis and surface hydrophobicity. RESULTS: LSP was mainly composed of eight subunits (18, 25, 31, 47, 51, 56, 65 and 151 kDa), in which the richest band was 25 kDa. FTIR results showed that LSP had high total contents of α-helix and ß-sheet (44.81-46.85%) in acidic environments. Meanwhile, there was more ß-structure and random structure in neutral and alkaline environments (pH 7.0 and 9.0). At pH 5.0, LSP had large particle size (1576.98 nm), high emulsion stability index (91.43 min), foaming stability (75.69%) and water holding capacity (2.21 g g-1), but low solubility (35.98%), free sulfhydryl content (1.95 µmol g-1) and surface hydrophobicity (780). DSC analysis showed the denaturation temperatures (82.23 °C) of LSP at pH 5.0 was higher than those (80.10, 80.52 and 71.82 °C) at pH 3.0, 7.0 and 9.0. The analysis of rheological properties showed that LSP gel had high stability and great strength in an alkaline environment. CONCLUSION: The findings of the present study are anticipated to serve as a valuable reference for the implementation of LSP in the food industry. © 2024 Society of Chemical Industry.

The structural characteristics and physicochemical properties of mung bean protein hydrolysate of protamex induced by ultrasound.

BACKGROUND: The limited physicochemical properties (such as low foaming and emulsifying capacity) of mung bean protein hydrolysate restrict its application in the food industry. Ultrasound treatment could change the structures of protein hydrolysate to accordingly affect its physicochemical properties. The aim of this study was to investigate the effects of ultrasound treatment on the structural and physicochemical properties of mung bean protein hydrolysate of protamex (MBHP). The structural characteristics of MBHP were evaluated using tricine sodium dodecylsulfate-polyacrylamide gel electrophoresis, laser scattering, fluorescence spectrometry, etc. Solubility, fat absorption capacity and foaming, emulsifying and thermal properties were determined to characterize the physicochemical properties of MBHP. RESULTS: MBHP and ultrasonicated-MBHPs (UT-MBHPs) all contained five main bands of 25.8, 12.1, 5.6, 4.8 and 3.9 kDa, illustrating that ultrasound did not change the subunits of MBHP. Ultrasound treatment increased the contents of α-helix, ß-sheet and random coil and enhanced the intrinsic fluorescence intensity of MBHP, but decreased the content of ß-turn, which demonstrated that ultrasound modified the secondary and tertiary structures of MBHP. UT-MBHPs exhibited higher solubility, foaming capacity and emulsifying properties than MBHP, among which MBHP-330 W had the highest solubility (97.32%), foaming capacity (200%), emulsification activity index (306.96 m2 g-1 ) and emulsion stability index (94.80%) at pH 9.0. CONCLUSION: Ultrasound treatment enhanced the physicochemical properties of MBHP, which could broaden its application as a vital ingredient in the food industry. © 2023 Society of Chemical Industry.

Changes in quality components and antioxidant activity of peony seed soy sauce during low-salt solid-state fermentation.

BACKGROUND: In this study, the fermentation conditions of peony seed soy sauce (PSSS) koji were optimized by response surface method, and the quality components and antioxidant activity of PSSS were investigated at different low-salt solid-state fermentation stages. RESULTS: Results of response surface method showed that the optimal fermentation conditions were 460.6 g kg-1 water content, 48.6 h culture time, 31.5 °C culture temperature and ratio 2.1:1 (w/w) of peony seed meal:wheat bran, with the highest neutral protease activity (2193.78 U g-1 ) of PSSS koji. PSSS had the highest amino acid nitrogen (7.69 g L-1 ), salt-free soluble solids (185.26 g L-1 ), total free amino acids (49.03 g L-1 ), essential free amino acids (19.58 g L-1 ) and umami free amino acids (16.64 g L-1 ) at 20 days of fermentation. The highest total phenolics were 5.414 g gallic acid equivalent L-1 and total flavonoids 0.617 g rutin equivalent L-1 , as well as the highest DPPH radical scavenging activity (86.19%) and reducing power (0.8802, A700 ) of PSSS fermented at 30 days. Sensory evaluation showed that fermentation of 20 days and 25 days could produce a better taste and aroma of PSSS than 15 days and 30 days. CONCLUSION: PSSS had the highest quality components in the middle of fermentation (20 days) and the highest antioxidant activity in the late fermentation period (30 days). These results demonstrated that peony seed meal could be used to produce high-quality soy sauce with high antioxidant activity. © 2023 Society of Chemical Industry.

Physicochemical, functional and antioxidant properties of mung bean protein enzymatic hydrolysates.

This study aimed to investigate physicochemical, functional and antioxidant properties of mung bean protein (MBP) enzymatic hydrolysates (MBPEHs) by alcalase, neutrase, protamex, flavourzyme and papain. Physicochemical properties were evaluated by SDS-PAGE, particle size distribution, FTIR, ultraviolet visible and fluorescence spectrophotometries. ABTS, hydroxyl scavenging, Fe2+ chelating activity were used to evaluate antioxidant activity. Enzymolysis with five proteases decreased average particle size, α-helix, ß-sheet, surface hydrophobicity of hydrolysates. Alcalase hydrolysate had the highest degree of hydrolysis (23.55%), absolute zeta potential (33.73 mV) and the lowest molecular weight (<10 kDa). Protamex and papain hydrolysates had higher foaming capacities, emulsification activity indexes, emulsion stability indexes (235.00%, 123.07 m2/g, 132.54 min; 200.10%, 105.39 m2/g, 190.67 min) than MBP (135.03%, 20.03 m2/g, 30.88 min). Alcalase hydrolysate demonstrated the lowest IC50 (mg/mL) in ABTS (0.12), hydroxyl (2.98), Fe2+ chelating (0.22). These results provide support for application of MBPEHs as foaming agent, emulsifier and antioxidant in food industry.

Influence of ultrasound treatment on the physicochemical and antioxidant properties of mung bean protein hydrolysate.

This study aimed to investigate influence of ultrasonic treatment on physicochemical and antioxidant properties of mung bean protein hydrolysate (MPH). Physicochemical properties of MPH were evaluated by Tricine-SDS-PAGE, particle size distribution, fourier transform infrared spectroscopy (FTIR) and fluorescence spectroscopy, among others. Radicals scavenging activities of ABTS, hydroxyl, superoxide anion, Fe2+ chelating ability and reducing power characterized antioxidant activities of MPH. MPH contained four bands of 25.6, 12.8, 10.6 and 4.9 kDa, in which 4.9 kDa was the most abundant. Ultrasonic treatment increased the contents of aromatic and hydrophobic amino acids in MPH. Ultrasonic treatment decreased the content of α-helix of MPH and increased ß-sheet and ß-turn compared to MPH. MPH-546 W (ultrasonic treatment 546 W, 20 min) had the lowest average particle size (290.13 nm), zeta potential (-36.37 mV) and surface hydrophobicity (367.95 A.U.). Antioxidant activities of ultrasonicated-MPH increased with the ultrasonic power, achieving the lowest IC50 (mg/mL) of 0.1087 (ABTS), 1.796 (hydroxyl), 1.003 (superoxide anion) and 0.185 (Fe2+ chelating ability) in 546 W power. These results indicated ultrasonic treatment would be a promising method to improve the antioxidant properties of MPH, which would broaden the application scope of MPH as bioactive components in the food industry.

Identification and Characterization of a High Efficiency Aniline Resistance and Degrading Bacterium MC-01.

Biodegradation is one of the important methods for the treatment of industrial wastewater containing aniline. In this paper, a degrading bacterium named MC-01, which could survive in high concentration aniline wastewater, was screened from industrial wastewater containing aniline and sludge. MC-01 was preliminarily identified as Ochrobactrum sp. based on the amplified 16S rDNA gene sequence and Biolog system identification. MC-01 was highly resistant to aniline. After 24-h culture under aniline concentration of 6500 mg/L, the amount of bacterium survived still remained 0.05 × 106 CFU/mL. Experiments showed that there was no coupling expression between the growth of MC-01 and aniline degradation. The optimum growth conditions in LB culture were pH 6.0, 30 °C of temperature, and 4% of incubation amount, respectively. And the optimum conditions of aniline degradation of MC-01 were pH 7.0, 45 °C of temperature, and 3.0% of salt concentration, respectively. The degradation rate of MC-01 (48 h) in different aniline concentrations (200~1600 mg/L) was stable under the optimum conditions, which could reach more than 75%.

STAT3 Undergoes Acetylation-dependent Mitochondrial Translocation to Regulate Pyruvate Metabolism.

Cytoplasmic STAT3, after activation by growth factors, translocates to different subcellular compartments, including nuclei and mitochondria, where it carries out different biological functions. However, the precise mechanism by which STAT3 undergoes mitochondrial translocation and subsequently regulates the tricarboxylic acid (TCA) cycle-electron transport chain (ETC) remains poorly understood. Here, we clarify this process by visualizing STAT3 acetylation in starved cells after serum reintroduction or insulin stimulation. CBP-acetylated STAT3 undergoes mitochondrial translocation in response to serum introduction or insulin stimulation. In mitochondria, STAT3 associates with the pyruvate dehydrogenase complex E1 (PDC-E1) and subsequently accelerates the conversion of pyruvate to acetyl-CoA, elevates the mitochondrial membrane potential, and promotes ATP synthesis. SIRT5 deacetylates STAT3, thereby inhibiting its function in mitochondrial pyruvate metabolism. In the A549 lung cancer cell line, constitutively acetylated STAT3 localizes to mitochondria, where it maintains the mitochondrial membrane potential and ATP synthesis in an active state.

[Lidamycin inhibits angiogenesis of zebrafish embryo via down-regulation of VEGF].

Lidamycin (LDM) is a potent antitumor antibiotic. Previous studies have shown that LDM could inhibit proliferation and migration in endothelial cells. In the present report, the effect of LDM on angiogenesis of zebrafish embryo was studied. The results showed that treatment of zebrafish embryos with LDM resulted in significant inhibition of angiogenesis. Morphological observation, quantitative endogenous alkaline phosphatase (EAP) assay, alkaline phosphatase staining, and transgenic zebrafish assay were performed to evaluate vascular development defects in zebrafish. The results indicated that after the zebrafish embryos were exposed to LDM, angiogenesis defects of zebrafish embryos were observed, including pericardial edema, reduced numbers of circulating red blood cells, suppression of zebrafish vessel growth, and absences of SIV (subintestinal vein). The expression of VEGF was detected by RT-PCR assay, quantitative reverse transcriptase real-time PCR (qRT-PCR) assay and Western blotting analysis. The results revealed that LDM could inhibit the expression of VEGF protein, while the expression of mRNA was not significantly affected. The study suggests that LDM could inhibit the zebrafish embryo angiogenesis by down-regulation ofVEGF expression.

[Update on host cell invasion by Toxoplasma gondii].

This paper reviewed the importance of micronemes, dense granules, rhoptry and major surface proteins of Toxoplasma gondii, and of calcium during the host cell invasion as well as the role of T. gondii proteases in the folding and processing of these proteins.