Structural Characterization and Antioxidant Activity of Walnut Peptides

This study prepared and structurally characterized peptides with different molecular masses from walnut meal protein by enzymatic hydrolysis with a mixture of two proteases followed by ultrafiltration, and it also explored the antioxidant activities of walnut peptides and their protective effects on oxidative damage in HepG2 cells. The results showed that the antioxidant activity of walnut protein hydrolysate (WPH) with molecular mass < 1 kDa was the strongest, with half-maximal inhibitory concentration (IC50) of 11.47, 35.67 and 49.72 mg/mL for hydroxyl radical, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation scavenging capacity, respectively. Moreover, the < 1 kDa walnut peptide fraction could reduce the reactive oxygen species (ROS) content and increase the superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GSH-Rx) and glutathione peroxidase (GSH-Px) activity in HepG2 cells. The walnut peptide was irregular in shape and had a smooth surface and dense structure with numerous rough patterns and pores. The walnut peptide had a maximum absorption peak at 225 nm wavelength. The most abundant secondary structures of the walnut peptide were random coil (36.5%) and β-sheet (36.6%). These results indicate that the < 1 kDa walnut peptide has a protective effect against oxidative damage in HepG2 cells

Isolation and extraction of glansreginin A from walnut meal and its effect on the proliferation of 3T3-L1 cells

Abstract Glansreginin A is an indicative component in walnut and is abundant in walnut meal. The aim of this study was to isolate and purify glansreginin A from the walnut meal, and to investigate the weight loss and lipid-lowering potential of glansreginin A by studying the effect of glansregin A on the proliferation of 3T3-L1 preadipocytes. Firstly, the response surface methodology was used to effectively improve the extraction yield of glansreginin A. The maximum extraction rate of glansreginin A was 0.363%, and the optimal extraction process conditions were determined. In addition, the lipid-lowering activity of glansreginin A was investigated by cell experiments. The results showed that glansreginin A could inhibit the proliferation of 3T3-L1 preadipocytes in a dose-dependent manner. And cell cycle of different groups of cells treated with glansreginin A was also measured using flow cytometry. The results showed most of the cells were blocked in G0/G1 phase and significantly decreased in S phase. These results suggest that glansreginin A could inhibit the proliferation of 3T3-L1 preadipocytes by causing cell cycle arrest. These findings provided a theoretical basis for the future research of glansreginin A and the development of slimming and fat-reducing foods

GRIM-19 Disrupts E6/E6AP Complex to Rescue p53 and Induce Apoptosis in Cervical Cancers

BACKGROUND: Our previous studies showed a down-regulation of GRIM-19 in primary human cervical cancers, and restoration of GRIM-19 induced tumor regression. The induction of tumor suppressor protein p53 ubiquitination and degradation by E6 oncoportein of high risk-HPV through forming a stable complex with E6AP is considered as a critical mechanism for cervical tumor development. The aims of this study were to determine the potential role of GRIM-19 in rescuing p53 protein and inducing cervical cancer cell apoptosis. METHODOLOGY/PRINCIPAL FINDINGS: The protein levels of GRIM-19 and p53 were detected in normal cervical tissues from 45 patients who underwent hysterectomy for reasons other than neoplasias of either the cervix or endometrium, and cervical cancer tissues from 60 patients with non-metastatic squamous epithelial carcinomas. Coimmunoprecipitation and GST pull-down assay were performed to examine the interaction of GRIM-19 with 18E6 and E6AP in vivo and in vitro respectively. The competition of 18E6 with E6AP in binding GRIM-19 by performing competition pull-down assays was designed to examine the disruption of E6/E6AP complex by GRIM-19. The augment of E6AP ubiquitination by GRIM-19 was detected in vivo and in vitro ubiquitination assay. The effects of GRIM-19-dependent p53 accumulation on cell proliferation, cell cycle, apoptosis were explored by MTT, flow cytometry and transmission electron microscopy respectively. The tumor suppression was detected by xenograft mouse model. CONCLUSION/SIGNIFICANCE: The levels of GRIM-19 and p53 were concurrently down regulated in cervical cancers. The restoration of GRIM-19 can induce ubiquitination and degradation of E6AP, and disrupt the E6/E6AP complex through the interaction of N-terminus of GRIM-19 with both E6 and E6AP, which protected p53 from degradation and promoted cell apoptosis. Tumor xenograft studies also revealed the suppression of p53 degradation in presence of GRIM-19. These data suggest that GRIM-19 can block E6/E6AP complex; and synergistically suppress cervical tumor growth with p53

Research Progress in Molecular Identification Technology for Microbial Resources

As the most widely distributed and abundant biological resources in the world, microbial resources have been applied in many fields and shown great economic and social values. Although there have been numerous previous studies on microorganisms, the studies could not be further launched owing to limited technical methods. However, the continuous development of microbial detection technologies now provides new approaches for microbial research. In this article, we summarize the molecular identification technologies and their application for microbial resources in China and abroad; these technologies include deoxyribonucleic acid (DNA) (G+C) mol% identification, nucleic acid hybridization, DNA fingerprinting, nucleic acid amplification, gene chips, and high throughput sequencing. Moreover, we summarize the advantages and disadvantages of each technology and analyze the problems faced by molecular identification of microbial resources, including reliance on laboratory environment, insufficient reproducibility and accuracy of experimental results, and lack of microbial databases. To protect and utilize microbial resources, China should strengthen the research of each identification technology, establish a microbial resource identification platform with independent intellectual property rights, and improve the microbial resource database

Dynamic Test and Analysis of Strength of Bamboo Curtain Plywood Based on Free Vibration Modal Method

Bamboo curtain plywood is made of equal-thickness slotted bamboo slivers as its constituent units and is formed into boards with high pressure. In this paper, rectangular plates, beam specimens, and two sizes of square plates were tested to determine the elastic modulus and shear modulus of bamboo curtain plywood quickly, easily, and accurately. The free square board torsional vibration method was used to test the shear modulus of the square plates. The dynamic test results were also verified by means of the static four-point bending method. The main conclusions show that the dynamic elastic modulus, shear modulus and Poisson's ratio of this bamboo curtain plywood are 0.7 GPa, 1300 MPa and 0.12, respectively. The values of the elastic constants of these bamboo curtain plywood specimens measured by dynamic and static methods are consistent, and this dynamic test method has the advantages of fast, easy, good repeatability and high accuracy

Selection, Identification, and Application of Aptamers against Agaricus bisporus Lectin to Establish an Aptamer-AuNPs Colorimetric Method for Detection of ABL

Agaricus bisporus lectin (ABL), which is one of the antinutritional factors in A. bisporus, is an important allergen and harmful to human health. Due to the shortcomings of the current detection methods, it is extremely urgent to establish a rapid and sensitive detection method for ABL in foods. To isolate the ssDNA aptamer of ABL, 13 rounds of subtractive systematic evolution of ligands by exponential enrichment (SELEX) selection were carried out. As a result, six candidate aptamers were selected and further examined for their binding affinity and specificity by enzyme-linked aptamer method. One aptamer (seq-41) against ABL with a high affinity and specificity was isolated and demonstrated to be the optimal aptamer whose dissociation constant reaches the nanomolar level, Kd = 31.17 ± 0.1070 nM. Based on seq-41, an aptamer-AuNPs colorimetric method was established to detect ABL with a linear range of 0.08∼1.70 μg/mL and the detection limit is 0.062 μg/mL. This study provides a novel aptamer-AuNPs colorimetric method with high sensitivity and specificity for detection of ABL and a novel strategy for development of detection method of fungal or plant allergens

Density Functional Theory Analysis of the Copolymerization of Cyclopropenone with Ethylene Using a Palladium Catalyst

Density functional theory has been used to elucidate the mechanism of Pd copolymerization of cyclopropenone with ethylene. The results reveal that introducing ethylene and cyclopropenone to Pd catalyst is thermodynamically feasible and generates the α,β-unsaturated ketone unit (UnitA). Cis-mode insertion and Path A1a are the most favorable reaction routes for ethylene and cyclopropenone, respectively. Moreover, cyclopropenone decomposition can generate CO in situ without a catalyst or with a Pd catalyst. The Pd-catalyzed decomposition of cyclopropenone exhibits a lower reaction barrier (22.7 kcal/mol) than its direct decomposition. Our study demonstrates that incorporating CO into the Pd catalyst can generate the isolated ketone unit (UnitB). CO is formed first; thereafter, UnitB is generated. Therefore, the total energy barrier of UnitB generation, accounting for the CO barrier, is 22.7 kcal/mol, which is slightly lower than that of UnitA generation (24.0 kcal/mol). Additionally, the possibility of copolymerizing ethylene, cyclopropenone, and allyl acetate (AAc) has been investigated. The free energy and global reactivity index analyses indicate that the cyclopropenone introduction reaction is more favorable than the AAc insertion, which is consistent with the experimental results. Investigating the copolymerization mechanism will help to develop of a functionalization strategy for polyethylene polymers

Preparation of glyco-silica materials via thiol-ene click chemistry for adsorption and separation

Glyco-silica materials were successfully developed based on thiol-ene click chemistry between alkene-saccharides and mercapto-silica, which behaved well in HILIC separation and exhibited high affinity to specific proteins