Biosynthesis of β-Glucosidase-Silk Fibroin Nanoparticles Conjugates and Enzymatic Characteristics

2011 ◽  
Vol 175-176 ◽  
pp. 186-191 ◽  
Author(s):  
Zhen Zhen Zhou ◽  
Yu Qing Zhang

Silk fibroin derived from Bombyx mori is a biomacromolecular protein with outstanding biocompatibility. When it was dissolved in highly concentrated CaCl2 solution and then the mixture of the protein and salt was subjected to desalting treatments for long time in flowing water, the resulting liquid silk was water-soluble polypeptides with different molecular masses, ranging from 10 to 200 kDa. When the liquid silk were introduced rapidly into acetone, silk protein nanoparticles (SFNs) with a range of 40~120 nm in diameter could be obtained. The crystalline silk nanoparticles could be conjugated with β-glucosidase with cross-linking of reagent glutaraldehyde. In this work, the activity of β-glucosidase-silk fibroin nanoparticles (βG-SFNs) bioconjugates was determined by p-nitrophenyl-β-D-glucoside (p-NPG) as a substrate and the optimal conditions for the biosynthesis of βG-SFNs bioconjugates were investigated. βG-SFN constructs obtained by 5h of covalent cross-linking time at the experimental conditions of 0.25% cross-linking reagent, 37 °C and the proportion of β-glucosidase and SFNs (75 : 100, U/mg) showed 46% of recoveries. Results showed that kinetic parameters of βG-SFNs were the same as for the free β-glucosidase. The optimal pH was 5.0 and the optimal temperature was 60°C. When β-glucosidase was coupled covalently with silk nanoparticles, the thermal stability of βG-SFNs was slightly enhanced as compared with free β-glucosidase. The apparent Km of βG-SFNs (1.41×10-3 mol•L-1) was near five-fold less than that of the free enzyme (7.26×10−3 mol•L-1), this fully shows that after the free enzyme conjugated with silk fibroin nanoparticles, the enzyme affinity with substrate increased. These results fully demonstrated the silk protein nanoparticles were good carriers as bioconjugation or modification of enzymes. Moreover, they had potential values for research and development in food processing and flavor processing agents.

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Min-Hui Wu ◽  
Lin Zhu ◽  
Zhen-Zhen Zhou ◽  
Yu-Qing Zhang

Bombyx mori silk fibroin is a macromolecular biopolymer with remarkable biocompatibility. It was degummed and subjected to a series of treatments, including dissolution and dialysis, to yield an aqueous solution of silk fibroin, which was introduced rapidly into excess acetone to produce crystalline silk fibroin nanoparticles (SFNs), which were conjugated covalently with naringinase using glutaraldehyde as the cross-linking reagent. The SFN naringinases are easily recovered by centrifugation and can be used repeatedly. Naringinase is a bienzyme consisting of α-L-rhamnosidase and flavonoid-β-glucosidase. The enzyme activity and its kinetics were similar to those of the native form, and the optimum reactive temperature for both is 55°C. In our study, centrifugation allowed the separation of enzyme and substrate; after eight cycles the SFN naringinases retained >70% residual activity. The highly efficient processing technology and the use of SFN as a novel vector for a bienzyme have great potential for research and the development of food processing such as the debittering of naringin-containing juices.


2020 ◽  
Vol 16 (7) ◽  
pp. 905-913
Author(s):  
Youyuan Peng ◽  
Qingshan Miao

Background: L-Ascorbic acid (AA) is a kind of water soluble vitamin, which is mainly present in fruits, vegetables and biological fluids. As a low cost antioxidant and effective scavenger of free radicals, AA may help to prevent diseases such as cancer and Parkinson’s disease. Owing to its role in the biological metabolism, AA has also been utilized for the therapy of mental illness, common cold and for improving the immunity. Therefore, it is very necessary and urgent to develop a simple, rapid and selective strategy for the detection of AA in various samples. Methods: The molecularly imprinted poly(o-phenylenediamine) (PoPD) film was prepared for the analysis of L-ascorbic acid (AA) on gold nanoparticles (AuNPs) - multiwalled carbon nanotubes (MWCNTs) modified glass carbon electrode (GCE) by electropolymerization of o-phenylenediamine (oPD) and AA. Experimental parameters including pH value of running buffer and scan rates were optimized. Scanning electron microscope (SEM), fourier-transform infrared (FTIR) spectra, cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were utilized for the characterization of the imprinted polymer film. Results: Under the selected experimental conditions, the DPV peak currents of AA exhibit two distinct linear responses ranging from 0.01 to 2 μmol L-1 and 2 to 100 μmol L-1 towards the concentrations of AA, and the detection limit was 2 nmol L-1 (S/N=3). Conclusion: The proposed electrochemical sensor possesses excellent selectivity for AA, along with good reproducibility and stability. The results obtained from the analysis of AA in real samples demonstrated the applicability of the proposed sensor to practical analysis.


Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1510
Author(s):  
Sylwia Grabska-Zielińska ◽  
Alina Sionkowska

This review supplies a report on fresh advances in the field of silk fibroin (SF) biopolymer and its blends with biopolymers as new biomaterials. The review also includes a subsection about silk fibroin mixtures with synthetic polymers. Silk fibroin is commonly used to receive biomaterials. However, the materials based on pure polymer present low mechanical parameters, and high enzymatic degradation rate. These properties can be problematic for tissue engineering applications. An increased interest in two- and three-component mixtures and chemically cross-linked materials has been observed due to their improved physico-chemical properties. These materials can be attractive and desirable for both academic, and, industrial attention because they expose improvements in properties required in the biomedical field. The structure, forms, methods of preparation, and some physico-chemical properties of silk fibroin are discussed in this review. Detailed examples are also given from scientific reports and practical experiments. The most common biopolymers: collagen (Coll), chitosan (CTS), alginate (AL), and hyaluronic acid (HA) are discussed as components of silk fibroin-based mixtures. Examples of binary and ternary mixtures, composites with the addition of magnetic particles, hydroxyapatite or titanium dioxide are also included and given. Additionally, the advantages and disadvantages of chemical, physical, and enzymatic cross-linking were demonstrated.


Author(s):  
Patricia Diez-Echave ◽  
Antonio Jesús Ruiz-Malagón ◽  
José Alberto Molina-Tijeras ◽  
Laura Hidalgo-García ◽  
Teresa Vezza ◽  
...  

Author(s):  
Haiyan Zheng ◽  
Baoqi Zuo

This article reviews the current status of the preparation, properties and application of functional silk protein hydrogels.


Drug Delivery ◽  
2021 ◽  
Vol 28 (1) ◽  
pp. 1626-1636
Author(s):  
Afrasim Moin ◽  
Shahid Ud Din Wani ◽  
Riyaz Ali Osmani ◽  
Amr S. Abu Lila ◽  
El-Sayed Khafagy ◽  
...  

1982 ◽  
Vol 205 (2) ◽  
pp. 361-372 ◽  
Author(s):  
E J Emanuel ◽  
A D Brampton ◽  
D R Burton ◽  
R A Dwek

The interaction between the complement subcomponent C1q and immunoglobulin G was investigated under a variety of experimental conditions. Formation of the subcomponent C1q-immunoglobulin G complex was shown to be an equilibrium process. Thermodynamic studies of the effect of varying the ionic strength indicate that over the salt range 0.15-0.225 M-NaCl the binding of subcomponent C1q to immunoglobulin aggregates releases 9-12 salt ions (Na+ and/or Cl-), illustrating the importance of ionic interactions for the formation of the complex. The effects of small peptide and organic ion inhibitors support this conclusion. Chemical modifications of carboxylate residues on immunoglobulin G by glycine ethyl ester/water-soluble carbodi-imide (up to 12 residues modified per whole molecule of immunoglobulin G) and of lysine residues by acetic anhydride (3 residues per whole molecule of immunoglobulin G) or methyl acetimidate (19 residues per whole molecule of immunoglobulin G) lowered the binding affinity of immunoglobulin for subcomponent C1q. Modification of arginine residues by cyclohexane-1,2-dione-1,2 (14 residues per whole molecule of immunoglobulin G) and of tryptophan by hydroxynitrobenzyl bromide (2 residues per whole molecule of immunoglobulin G), however, had little or no effect. The results are consistent with the proposal that the subcomponent-C1q-binding site on immunoglobulin G is to be found on the last two beta-strands of the Cv2 domain [Burton, Boyd, Brampton, Easterbrook-Smith, Emanuel, Novotny, Rademacher, van Schravendijk, Sternberg & Dwek (1980) Nature (London) 288, 338-344].


2017 ◽  
Vol 9 (37) ◽  
pp. 31600-31611 ◽  
Author(s):  
Fatemeh Mottaghitalab ◽  
Melika Kiani ◽  
Mehdi Farokhi ◽  
Subhas C. Kundu ◽  
Rui L. Reis ◽  
...  

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