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A rational design method to improve ß-mannanase (ManTJ102) thermostability was developed successfully in this study. The flexible area of residues 330-340 in ManTJ102 was firstly selected from analysis of molecular dynamics simulation and then the critical amino acid residue (Ala336Pro) with the lowest mutation energy was determined by virtual mutation, whose mutant was named as Mutant336. Afterward, the dynamics transition temperature (Tdtt) of ManTJ102 and Mutant336 was evaluated by simulated annealing and heating, and Mutant336 with higher Tdtt was implemented for experimental verification of the enzyme thermostability. As a result, the half-life of Mutant336 activity was 120 min at 60 °C, which was 24-fold of ManTJ102, and the irreversible thermal denaturation constant of Mutant336 was only about 2/5 of ManTJ102, indicating that Mutant336 has better thermostability than ManTJ102. Furthermore, Mutant336 has much higher ß-mannanase activity and specific activity than ManTJ102. Therefore, Mutant336 was more suitable to further research for applications.

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The spectrum of optical fiber surface plasmon resonance (SPR) shows the characteristics of wider full width at half-maximum (FWHM) and smaller peak value. The traditional peak detection algorithm cannot calculate the resonance wavelength of this kind of spectrum accurately. Therefore, efficient methods to calculate the resonance wavelength are required. This paper presents a method to process the SPR signal based on the Gaussian fitting. Combined with the trust region algorithm to determine the Gaussian fitting function, and then the resonance wavelength be calculated by line search method. Data processing of standard spectrum of glycerin with different concentration proves that this algorithm can adapt to optical fiber SPR spectrum characteristics, and calculate resonance wavelength accurately. The experiment measures the SPR signals of sucrose under different concentrations through the self-building SPR measure system. By using the proposed method, the weighted centroid method and the tracking centroid method to calculate the resonance wavelength, the result shows that the Gaussian fitting method can effectively improve resolution and have a short operation time which is conducive to engineering application.

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Natural oligomeric procyanidin (OPC) with high biological and pharmacological activities was successfully used to synthesize OPC-insulin (OPC-INS) nanoparticles with different aggregation sizes for sustained and controlled delivery of hydrophilic insulin. The aggregation size of OPC-INS nanoparticles was regulated by OPC concentration, pH value, and incubation time. The fabrication mechanism would be that OPC and insulin self-assembled into a mixture of insulin aggregates via intermolecular interactions. In the self-assembly of insulin, OPC could serve both in the encompassing of insulin aggregates as a stabilizer and cross-linking different amounts of insulin aggregates into OPC-INS nanoparticles as interphase. OPC-INS nanoparticles not only demonstrated effective insulin drug loading but also exhibited aggregation-size-dependent and controlled insulin release performance in vitro. In the best case for OPC-INS nanoparticles, only ∼21% of insulin was released in 37 days. This study showed that the OPC-INS nanosystem is promising to serve as a long-acting insulin release formulation, and OPC has great potential as a drug carrier for nanomedicine.

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Cellobiase can hydrolyze cellobiose into glucose; it plays a key role in the process of cellulose hydrolysis by reducing the product inhibition. To reuse the enzyme and improve the economic value of cellulosic ethanol, cellobiase was immobilized using sodium alginate and chitosan as carriers by the bubbling method. The immobilization conditions were optimized as follows: enzyme loading of 100 U cellobiase/g carrier, 30 min immobilization, 3.5 wt% sodium alginate, 0.25 wt% chitosan, and 2 wt% calcium chloride. Compared to free enzyme, the immobilized cellobiase had a decreased apparent K(m) and the maximum activity at a lower pH, indicating its higher acidic and thermal stability. The immobilized cellobiase was further tested in the hydrolysis of cellobiose and various cellulosic substrates (microcrystalline cellulose, filter paper, and ammonia-pretreated corn cobs). Together with cellulases, the immobilized cellobiase converted the cellulosic substrates into glucose with the rate and extent similar to the free enzyme.

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Bovine hemoglobin was hydrolyzed with pepsin in a batch stirred tank reactor; the resulting peptides were identified, in a time dependent and comprehensive manner, using reversed phase-high performance liquid chromatography (RP-HPLC) coupled with electrospray ionization tandem mass spectrometry (ESI-MS/MS) by means of database searching. Peptic digestion of bovine hemoglobin yields more hydrophobic peptides at a low degree of hydrolysis, and more hydrophilic peptides at a later stage of hydrolysis. The release kinetics of the bioactive peptides was also followed based on the RP-HPLC profiles. In addition, the behavior of peptic digestion of hemoglobin alpha and beta chains was compared in terms of profiling the identified peptides. Thirty-two peptides were recovered by a process of hydrolysis from the alpha chain of the peptide; whereas the corresponding result for the beta chain was 19 peptides with around 67% sequence coverage. The main factor responsible for non-peptic susceptibility of the central region of the beta chain was their relatively higher hydrophilicity.

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