Effect of protease hydrolysis on the structure of acidic heating-induced soy protein amyloid fibrils

The effectiveness of using amyloid fibrillation to improve the functional qualities of soy protein had drawn growing attention. However, the relationship between protein subunits and the structural polymorphism of soy protein-derived amyloid fibrils (SAFs) was not yet completely understood. In this study, soy protein subunits were hydrolyzed to different degrees according to the different action sites of different proteases (Pepsin, Papain and Alcalase). The impact of subunits on the amyloid fibrillation of soy protein was investigated through various techniques including atomic force microscopy, thioflavin T fluorescence, 1-anililo-naphthalene-8-sulfonate, and Fourier transform infrared spectrometer. The findings showed that the α and α' subunits were associated with the formation of fibril branch chains. The degree of hydrolysis of β subunits was found to be proportional to the number of fibrils. The presence of the 11S component was identified as a necessary condition for the formation of long-rigid fibrils. Furthermore, enzymatic hydrolysis unfolded the protein structure, exposing hydrophobic groups, loosening the protein structure, and altering the proportion of parallel and antiparallel β-sheet structures. This promoted the formation of amyloid fibrils and accelerated the development of stable SAFs gel. This study advances the knowledge of the function of subunits in amyloid fibrillation.

Optimization and Detergent Compatibility of Protease Produced from Aspergillus oryzae by Utilizing Agro Wastes

The biotechnological process called solid-state fermentation (SSF) was applied for hyper production of protease by using a fungal strain called Aspergillus oryzae. From screening of 9 different local substrates (peanut shell, wheat bran, guava leaves, sugar cane bagasse, rice polish, wheat straw, corn straw, reed grass, and rice straw), peanut shells serve as the best substrates for protease production under optimized cultured conditions. The varying physiochemical parameters such as pH (2-9.5), temperature (30-52 °C), incubation time (1-10 days), inoculum size (1-8 mL), moisture level (20-125%), and substrate concentration (1-7 g) were optimized by response surface methodology (RSM). The highest activity of protease was recorded to be 1101.778 U/mL at 660 nm using peanut shell was optimum at pH 8, temperature 52 °C, incubation time 8 days, inoculum size 2 mL, moisture level 20%, and substrate concentration 2 g. The crude form of enzymes produced were further purified through ammonium sulfate precipitation, dialysis, and gel filtration chromatography. Then, purified enzymes were characterized at different pH, temperature, and incubation time. For characterization of purified protease, pH, temperature, and incubation time were 8, 52 °C, and 8 days for peanut shell and was done by one factor at a time method. Hence, isolated enzymes were alkaline in nature, i.e., alkaline proteases. Then, protease produced from peanut shells was applied to locally available detergents to increase their catalytic activity for strain removal. At last, the final results were interpreted in the form of 3D surface and contour plots using Microsoft Excel 2013 and Minitab 17 software. In conclusion, the utilization of A. oryzae and peanut shell as the substrate in the biotechnological process of SSF demonstrated successful hyper production of alkaline protease. The optimized conditions resulted in high enzyme activity and showcased the potential application of the isolated enzymes in improving the catalytic activity of locally available detergents.

Synergistic inhibition of Pseudomonas fluorescens growth and proteases activities via sodium chlorite-based oxyhalogen

Pseudomonas fluorescens is considered among the main spoilage microorganisms due to its ability to produce proteases. Food deterioration caused by spoilage microorganisms has a major impact on food quality and the environment. The inactivation of Pseudomonas fluorescens growth and protease production was intensively investigated with the use of Salmide®, A Sodium Chlorite-Based Oxy-halogen Disinfectant. A unique M9 media was also developed to assure sufficient protease productions with different mutants of Pseudomonas fluorescens as a microbioreactor. Mutations were induced by classical whole-cell mutagenesis using N-methyl-N'- nitro-N-nitrosoguanidine (NTG). A dramatic decrease occurred in protease activity when different Salmide concentrations (5, 10, and 15 ppm) were added to the growth culture followed by a complete inhibition concentration (20, 25, 50, and 100 ppm) of Salmide. However, no significant inhibition occurred once it is secreted out of cells. Some mutants were resistant and remains highly stable with high protease production under stressful conditions of Sodium Chlorite-Based Oxy-halogen. The production of the protease showed a linear correlation with the increase in incubation time using a continuous culture bioreactor system and recorded maximum protease activity after 40 h. Our findings would offer alternative antimicrobial procedures for food and industrial sectors.

Biochemical, thermodynamic and structural characteristics of a biotechnologically compatible alkaline protease from a haloalkaliphilic, Nocardiopsis dassonvillei OK-18

This report describes purification strategies, biochemical properties and thermodynamic analysis of an alkaline serine protease from a marine actinomycete, Nocardiopsis dassonvillei strain OK-18. The solvent tolerance, broad thermal-pH stability, favourable kinetics and thermodynamics suggest stability of the enzymatic reaction. The enzyme was active in the range of pH 7-12 and 37-90 °C, optimally at pH 9 and 70 °C. The deactivation rate constant (Kd), half-life (t½), enthalpy (ΔH*), entropy (ΔS*), activation energy (E) and change in free energy (ΔG*) suggested stability and spontaneity of the reaction. β-Sheets as revealed by the Circular dichroism (CD) spectroscopy, were the major elements in the secondary structure of the enzyme, while Fourier-transform infrared spectroscopy (FTIR) indicated the presence of amide I and amide II. Based on the liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF-MS) analysis, the amino acid sequence had only 38% similarity with other proteases of Nocardiopsis strains, suggesting its novelty. The Ramachandran Plot revealed the location of the amino acid residues in the most favored region. The blood de-staining, gelatin hydrolysis, silver recovery and deproteinization of crab shells established the biotechnological potential of the enzyme.

The overexpression of the SAPB of Bacillus pumilus CBS and mutated sapB-L31I/T33S/N99Y alkaline proteases in Bacillus subtilis DB430: new attractive properties for the mutant enzyme

The sapB gene encoding for Bacillus pumilus CBS protease (SAPB) and the triple mutated sapB-L31I/T33S/N99Y gene were cloned and overexpressed in the protease-deficient Bacillus subtilis DB430 using an Escherichia coli-Bacillus shuttle vector pBSMuL2. The 34,625.13 and 34,675.11-Da enzymes were purified from the culture supernatant of B. subtilis expressing the wild-type and mutated genes, respectively. The purified proteases showed the same N-terminal sequences and biochemical properties of those expressed in E. coli. Further investigations demonstrated that, compared to wild-type and other proteases, SAPB-L31I/T33S/N99Y had the highest catalytic efficiency and the best degree of hydrolysis. The mutant enzyme was also noted to exhibit a number of newly explored properties that are highly valued in the marketplace, namely considerable stability to detergents, higher resistance towards organic solvents, and potent dehairing ability. Overall, the findings indicated that SAPB-L31I/T33S/N99Y is a promising candidate for future use in a wide range of industrial and commercial applications.

Inorganic compounds have dual effect on recombinant protein production: influence of anions and cations on serine alkaline protease production

AIMS

Investigation of concerted effects of cations, i.e. Mg2+ and Mn2+, in combination with their anions, i.e. sulphate, chloride and acetate (Ac), on the physiology of Bacillus licheniformis carrying pHV1431::subC to improve the fermentation medium for serine alkaline protease (SAP) production, whereupon, determination of the acid that can be used in pH control.

METHODS AND RESULTS

The cell concentrations increased with the increase in MnSO4 and Mn(Ac)2 concentrations, and the highest values were obtained at Co(MnSO4) = 0.20 mmol l-1 and Co(Mn(CH3COO)2) = 4.0 mmol l-1, as 2.3 and 2.2 g l-1, respectively. However, Co(MnCl2) did not influence biomass concentration. SAP production was inhibited with MnCl2 after Co(MnCl2) = 0.60 mmol l-1, but with MnSO4 SAP production was inhibited drastically. Whereas, at high concentrations of Mn(Ac)2 SAP production increased and the highest activity was obtained as ASAP = 1285 U ml-1 at t = 65 h. With the Mg compounds, cell concentrations increased with the increase in the concentrations of MgSO4, MgCl2 and Mg(Ac)2; and the anions did not show any influence on the cell growth. Similar to the results of Mn compounds, the glucose consumption rate increased with the increase in MgSO4 and MgCl2 concentrations; contrariwise, decreased with the increase in Mg(Ac)2 concentrations, due to the use of acetate as the second carbon source. Co(MgSO4) = 0.40 mmol l-1, Co(MgCl2) = 1.60 mmol l-1 and Co(Mg(Ac)2) = 0.40 mmol l-1 were the optimum concentrations separately, and the highest SAP activity was obtained with Mg(Ac)2 as ASAP = 1338 U ml-1 at t = 47 h. Consequently, ion acetate and its acid HAc appear, respectively, as the superior anion for the essential cations and the control agent for pH control in the bioreactor. Finally, optimum initial concentrations and the concerted effects of Mg(Ac)2 and Mn(Ac)2 were investigated, and the optimum concentrations were found respectively as 0.40 and 0.80 mmol l-1, while the maximum activity was obtained as ASAP = 1010 U ml-1 at a shortened cultivation time of t = 39 h.

CONCLUSIONS

Mn(Ac)2 and Mg(Ac)2 together enhanced the cell formation and SAP synthesis rates, moreover, SAP synthesis started at an earlier cultivation time.

SIGNIFICANCE AND IMPACT OF THE STUDY

Each inorganic compound with its cation and anion has dual effect on the metabolism. Mg2+ and Mn2+ at their specific concentrations influence the regulation of the pathways that might cause better coupling of supply and demand for the amino acids on the basis of the amino acid composition of the enzyme molecule.

Carbon sources affect metabolic capacities of Bacillus species for the production of industrial enzymes: theoretical analyses for serine and neutral proteases and α-amylase

The metabolic fluxes through the central carbon pathways were calculated for the genus Bacillus separately for the enzymes serine alkaline protease (SAP), neutral protease (NP) and alpha-amylase (AMY) on five carbon sources that have different reduction degrees (gamma), to determine the theoretical ultimate limits of the production capacities of Bacillus species and to predict the selective substrate for the media design. Glucose (gamma=4.0), acetate (gamma=4.0), and the TCA cycle organic-acids succinate (gamma=3.5), malate (gamma=3.0), and citrate (gamma=3.0) were selected for the theoretical analyses and comparisons. A detailed mass flux balance-based general stoichiometric model based on the proposed metabolic reaction network starting with the alternative five carbon sources for the synthesis of each enzyme in Bacillus licheniformis that simulates the behaviour of the metabolic pathways with 107 metabolites and 150 reaction fluxes is developed. Highest and lowest specific cell growth rates (&mgr;) were calculated as 1.142 and 0.766h(-1), respectively, when glucose that has the highest degree of reduction and citrate that has the lowest degree of reduction were used as the carbon sources. Highest and lowest SAP, NP and AMY synthesis rates were also obtained, respectively, when glucose and citrate were used. Metabolic capacity analyses showed that the maximum SAP, NP, and AMY synthesis rates were, respectively, 0.0483, 0.0215 and 0.0191mmolg(-1)DWh(-1) when glucose uptake rate was 10mmolg(-1)DWh(-1) and specific growth rate was zero. The amino acid compositions and the molecular weights of the enzyme influence the production yield and selectivity. For SAP and NP oxaloacetate and pyruvate, for AMY oxaloacetate appear to be the critical main branch points. Consequently, for SAP and NP syntheses the fluxes towards the alanine group and aspartate group, and for AMY synthesis the flux towards the aspartate group amino acids need to be high. The results encourage the discussion of the potential strategies for improving productions of SAP, NP and AMY.