Isolation and identification of thrombin-inhibiting peptides derived from soybean protein

The aim of this study was preparation of a soybean protein hydrolyzate with thrombin inhibitory activity and isolation, identification, and characterization of the active peptides from the hydrolyzate. In this study, a soybean protein hydrolyzate with the thrombin inhibiting IC50 value of 2.78 mg/mL was prepared under the improved pepsin hydrolysis condition, which exhibited the highest thrombin inhibitory activity in these soybean protein-derived hydrolyzates. A novel nonapeptide FFPDIPKIK with the IC50 value of 2.36 mM was screened from the hydrolyzate by in silico methods. The kinetic studies and molecular docking showed that the nonapeptide adopted a mixed-type mode to inhibit thrombin and bound with thrombin with several hydrogen bonds and hydrophobic interactions. The nonapeptide was partially digested using the in vitro digestion model, and its truncated peptides had comparable thrombin inhibitory activity. The results suggested that soybean protein hydrolyzate could be exploited as a functional food ingredient against coagulation.</p

Primers used for amplicon sequencing and qRT-PCR.

Soil quality is an important determinant of soil-use efficiency in the Loess Plateau. However, there is no in-depth study on the soil quality of the Loess Plateau. The present study compared the quality of the 0–20 cm soil layer (T0-20) and the 20–40 cm soil layer (T20-40) from the Guyuan region located in the Loess Plateau. The analysis revealed that T0-20 had a higher content of total N, total P, available P, and organic matter, and the activities of microbial enzymes, especially β-grape-glycosidase (β-GC) and sucrase (SC), than T20-40, indicating that soil quality in T0-20 was better than T20-40. Amplicon sequencing found that Pseudombrophila from Ascomycota was the most abundant microbial species and significantly differed between T0-20 (34.2%) and T20-40 (48.7%). This species and another 19 microbial species, such as Ceratobasidiaceae and Mortierellaceae, determined the diversity of soil microorganism. Further analysis of the phenotype and other parameters of pepper seedlings subjected to P. capsici infection isolated from test soil revealed that decreased organic matter content in deep soil layer is related to happening of pepper blight, and 3 h after infection was the critical time point for infection. The peroxidase (POD) activity increased after P. capsici infection and was positively correlated with infection time, suggesting this enzyme may be an indicator of pepper blight occurrence. These findings provide a theoretical foundation for planning pepper blight management and crop cultivation strategies in the Guyuan region.</div

Phenotype of pepper after were infected by P. phytophthora.

Phenotype of pepper after were infected by P. phytophthora.</p

Kits used for measurement of microorganism activity in this study.

Kits used for measurement of microorganism activity in this study.</p

Analysis of correlation index between the activities of antioxidant enzymes and infection time R² represents the correlation index, and the significant relation when R² is more than 0.8.

The assessment of R2 is based on the data from he levels of antioxidant enzyme activities.</p

Analysis of transcriptional levels of key genes encoding POD.

(A) CaPOD2 (B) CaPOD10 (C) CaPOD41 (D) CaPOD42 (E) CaPOD45 (F) CaPOD51 The leaves were sampled at the 4-leafed-6-leafed stage. The experiment was conducted with triplicates. The lowercase means the significance at p < 0.05 level, and the bar represented the SD of triplicates.</p

Characteristics of diversity in microorganism structure from T0-20 and T20-40.

(A) heat map involved in their abundance information (B) phylogenetic tree of genus level species (C) cladogram of phylogenetic distribution based on Lefese analysis. The top 35 genera were selected at the species level according to microorganism abundance information in each sample, thereby generating heat map. Phylogenetic tree is drawn based on the representative sequences of top 100 genera obtained by multiple sequence alignment. The data was analyzed based on amplicon sequencing of soil samples, and each soil sample includes triplicates.</p

Abbreviation list.

Soil quality is an important determinant of soil-use efficiency in the Loess Plateau. However, there is no in-depth study on the soil quality of the Loess Plateau. The present study compared the quality of the 0–20 cm soil layer (T0-20) and the 20–40 cm soil layer (T20-40) from the Guyuan region located in the Loess Plateau. The analysis revealed that T0-20 had a higher content of total N, total P, available P, and organic matter, and the activities of microbial enzymes, especially β-grape-glycosidase (β-GC) and sucrase (SC), than T20-40, indicating that soil quality in T0-20 was better than T20-40. Amplicon sequencing found that Pseudombrophila from Ascomycota was the most abundant microbial species and significantly differed between T0-20 (34.2%) and T20-40 (48.7%). This species and another 19 microbial species, such as Ceratobasidiaceae and Mortierellaceae, determined the diversity of soil microorganism. Further analysis of the phenotype and other parameters of pepper seedlings subjected to P. capsici infection isolated from test soil revealed that decreased organic matter content in deep soil layer is related to happening of pepper blight, and 3 h after infection was the critical time point for infection. The peroxidase (POD) activity increased after P. capsici infection and was positively correlated with infection time, suggesting this enzyme may be an indicator of pepper blight occurrence. These findings provide a theoretical foundation for planning pepper blight management and crop cultivation strategies in the Guyuan region.</div

Inhibition of Bubble Coalescence by Electrolytes in Binary Mixtures of Dimethyl Sulfoxide and Propylene Carbonate

We have investigated the effect of solvent composition on inhibition of bubble coalescence by electrolytes in binary mixtures of dimethyl sulfoxide (DMSO) and propylene carbonate (PC). Unlike most mixtures, combinations of DMSO and PC exhibit minimal foaming over all compositions (with the strongest effect being at 25% PC by volume); thus, the influence of electrolytes can be investigated. Both LiBr and KSCN at moderate concentrations inhibit bubble coalescence at all solvent compositions. However, the concentration of electrolyte required to inhibit coalescence was in both cases a minimum at the PC(v/v) of 25%. The surface tension of electrolyte solutions in the mixed solvents indicates that the gradient in surface tension is not correlated with coalescence inhibition and therefore inhibition cannot be attributed to surface elasticity. We have also studied the inhibition of bubble coalescence by HCl at different solvent compositions. HCl is strongly inhibitory in DMSO but only weakly so in PC. We have found that HCl exhibits strong inhibition behavior at all mixtures studied. All electrolytes studied were most effective at inhibiting bubble coalescence at the PC(v/v) of 25%, indicating that the interactions between solvent molecules strongly determine the influence of electrolyte on coalescence inhibition. We propose that the formation of solvent complexes between DMSO and PC results in an increase in surface viscosity and the presence of electrolytes further amplifies this effect

Leaf phenotype in pepper plants subjected to the infection of <i>P</i>. <i>capsici</i>.

The leaves were infected using P. capsici at the 3-leafed-4-leafed stage of pepper. Samples were collected at 1 h, 3 h, 6 h, 12 h and 24 h post infection. The leaf veins were used as the dividing line, agar plugs of the media with the strain were placed on the right side of the leaf veins, while another side do same treatment with water instead of agar plugs of the media as the control. The red circle represents the site of syndrome of pepper blight. The experiment was conducted with three biological replicates, and each replicate contained three pepper seedlings.</p