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61.
Dani Permana Kosuke Minamihata Tsuneyuki Tatsuke Jae M. Lee Takahiro Kusakabe Masahiro Goto Noriho Kamiya 《Biotechnology journal》2019,14(6)
The polymerization of proteins can create newly active and large bio‐macromolecular assemblies that exhibit unique functionalities depending on the properties of the building block proteins and the protein units in polymers. Herein, the first enzymatic polymerization of horseradish peroxidase (HRP) is reported. Recombinant HRPs fused with a tyrosine‐tag (Y‐tag) through a flexible linker at the N‐ and/or C‐termini are expressed in silkworm, Bombyx mori. Trametes sp. laccase (TL) is used to activate the tyrosine of Y‐tagged HRPs with molecular O2 to form a tyrosyl‐free radical, which initiates the tyrosine coupling reaction between the HRP units. A covalent dityrosine linkage is also formed through a HRP‐catalyzed self‐crosslinking reaction in the presence of H2O2. The addition of H2O2 in the self‐polymerization of Y‐tagged HRPs results in lower activity of the HRP polymers, whereas TL provides site‐selectivity, mild reaction conditions and maintains the activity of the polymeric products. The cocrosslinking of Y‐tagged HRPs and HRP‐protein G (Y‐HRP‐pG) units catalyzed by TL shows a higher signal in enzyme‐linked immunosorbent assay (ELISA) than the genetically pG‐fused HRP, Y‐HRP‐pG, and its polymers. This new enzymatic polymerization of HRP promises to provide highly active and functionalized polymers for biomedical applications and diagnostics probes. 相似文献
62.
Background
The anterior cruciate ligament rupture is a common injury which mainly affects young and active population. Faced to this problem, the development of synthetic structures for ligament reconstruction is increasing. The most recent researches focused on the development of biodegradable structures that could be functionalized to enhance host integration. This work describes the elaboration of different poly(ε-caprolactone) prototypes for the rat anterior cruciate ligament replacement in order to found the best design for further in vivo assays.Methods
According to the literature, it was decided to elaborate two different poly(ε-caprolactone) prototypes: a braided one and a free-fibers one. A chemical grafting of a bioactive polymer–poly(sodium styrene sulfonate) – was performed on both prototypes and mechanical and biological testing were assessed. Based on these results, one rat was implanted with the best prototype.Results
The mechanical and biological results demonstrated that the best prototype to implant was the poly(sodium styrene sulfonate)-grafted braided prototype. After one-month implantation, no inflammation was observable around the scar. The rat demonstrated good flexion and extension of the lower limb without any anterior drawer. The prototype was highly anchored to the bone. ESEM images of the explanted prototype showed the presence of cells and tissue ingrowth along and around the fibers.Conclusion
This work demonstrates the feasibility to implant a bioactive and biodegradable synthetic ligament in the rat model without any inflammation and with a good tissue anchoring at a short-term time. This will lead to an extensive in vivo assay. 相似文献63.
壳聚糖的化学改性及其在生物医药领域的应用进展 总被引:1,自引:0,他引:1
本文综述了近年来壳聚糖的酰化、羧甲基化、接枝、烷基化和交联等化学改性方法及其在生物医用高分子方面的应用进展,总结了壳聚糖改性及其应用过程中存在的问题并对其发展趋势作了预测。 相似文献
64.
Emre Cevik Mustafa Buyukharman Huseyin Bekir Yildiz 《Biotechnology and bioengineering》2019,116(4):757-768
In this study, gold electrodes (GE) were coated with conducting polymers to obtain a high photocurrent using cyanobacteria from a novel bioelectrochemical fuel cell. For this purpose, 4-(4H-ditiheno[3,2-b:2',3'-d]pyrol-4-yl) aniline and 5-(4H-dithieno[3,2-b:2',3'-d]pyrol-4-yl) napthtalane-1-amine monomers were coated on GE by performing an electropolymerization process. After that, gold nanoparticles (AuNP) were specifically modified by 2-mercaptoethane sulfonic acid and p-aminothiophenol to attach to the electrode surface. The conducting polymers GE coat was modified with functionalized AuNP using a cross-linker. The resulting electrode structures were characterized by cyclic voltammetry and chronoamperometry under on-off illumination using a fiber optic light source. Cyanobacteria Leptolyngbia sp. was added to the GE/conducting polymer/AuNP electrode surface and stabilized by using a cellulose membrane. During the illumination, water was oxidized by the photosynthesis, and oxygen was released. The released oxygen was electrocatalytically reduced at the cathode surface and a 25 nA/cm 2 photocurrent was observed in GE/ Leptolyngbia sp. After the electrode modifications, a significant improvement in the photocurrent up to 630 nA/cm 2 was achieved. 相似文献
65.
Jason E. Chung Hannah R. Joo Jiang Lan Fan Daniel F. Liu Alex H. Barnett Supin Chen Charlotte Geaghan-Breiner Mattias P. Karlsson Magnus Karlsson Kye Y. Lee Hexin Liang Jeremy F. Magland Jeanine A. Pebbles Angela C. Tooker Leslie F. Greengard Vanessa M. Tolosa Loren M. Frank 《Neuron》2019,101(1):21-31.e5
66.
67.
Metabolic flux modeling of detoxification of acetic acid by Ralstonia eutropha at slightly alkaline pH levels 总被引:8,自引:0,他引:8
Ralstonia eutropha grows on and produces polyhydroxyalkanoates (PHAs) from fermentation acids. Acetic acid, one major organic acid from acidogenesis of organic wastes, has an inhibitory effect on the bacterium at slightly alkaline pH (6 g HAc/L at pH 8). The tolerance of R. eutropha to acetate, however, was increased significantly up to 15 g/L at the slightly alkaline pH level with high cell mass concentration. A metabolic cell model with five fluxes is proposed to depict the detoxification mechanism including mass transfer and acetyl-CoA formation of acetic acid and the formation of three final metabolic products, polyhydroxybutyrate (PHB), active biomass, and CO(2). The fluxes were measured under different conditions such as cell mass concentration, acetic acid concentration, and medium composition. The experimental results indicate that the acetate detoxification by high cell mass concentration is attributed to the increased fluxes at high extracellular acetate concentrations. The fluxes could be doubled to reduce and hence detoxify the accumulated intracellular acetate anions. 相似文献
68.
Lee JC Bermudez H Discher BM Sheehan MA Won YY Bates FS Discher DE 《Biotechnology and bioengineering》2001,73(2):135-145
Vesicles made completely from diblock copolymers-polymersomes-can be stably prepared by a wide range of techniques common to liposomes. Processes such as film rehydration, sonication, and extrusion can generate many-micron giants as well as monodisperse, approximately 100 nm vesicles of PEO-PEE (polyethyleneoxide-polyethylethylene) or PEO-PBD (polyethyleneoxide-polybutadiene). These thick-walled vesicles of polymer can encapsulate macromolecules just as liposomes can but, unlike many pure liposome systems, these polymersomes exhibit no in-surface thermal transitions and a subpopulation even survive autoclaving. Suspension in blood plasma has no immediate ill-effect on vesicle stability, and neither adhesion nor stimulation of phagocytes are apparent when giant polymersomes are held in direct, protracted contact. Proliferating cells, in addition, are unaffected when cultured for an extended time with an excess of polymersomes. The effects are consistent with the steric stabilization that PEG-lipid can impart to liposomes, but the present single-component polymersomes are far more stable mechanically and are not limited by PEG-driven micellization. The results potentiate a broad new class of technologically useful, polymer-based vesicles. 相似文献
69.
Lac repressor protein was purified from E. coli BMH8117 harboring plasmid pWB1000 and E. coli K12BMH 71-18 strains. Displacement of the protein with poly(ethyleneimine) (PEI) from phosphocellulose cation exchange column was shown to be an effective elution strategy. It resulted in better recoveries and sharper elution profiles than traditional salt elution without effecting the purity of the protein. The elution is assumed to proceed via displacement of bound protein by PEI when the polymer binds to the ion exchanger. The minor impurities in the protein solution were finally removed by chromatography on immobilized metal affinity column. The repressor protein undergoes distinct conformational changes upon addition of specific inducer isopropyl--D-thiogalactoside (IPTG), which is evidenced by changes in ultraviolet absorption spectrum. The protein was immobilized covalently to the Sepharose matrix. The intact biological activity of the protein after immobilization was shown by binding of genomic DNA and lac operator plasmid DNA from E. coli to the immobilized lac repressor. 相似文献
70.
Mohri Fumihito Yoshizawa Kazunari Yambe Tokio Ishida Takashi Nogami Takashi 《Molecular Engineering》1999,8(4):357-373
Magnetic interactions in the three copper(II)-complex polymers, [Cu(PZ)(NO3)2]n, [Cu(PM)(NO3)2(H2O)2]n, and [Cu(PM)2(NO3)2]n are discussed on the basis of extended Hückel calculations inthe formulas PZ and PM stand for pyrazine and pyrimidine, respectively. Interactions between the Cu-3d orbitals and the lone-pair orbitals of pyrazine and pyrimidine are analyzed from the viewpoint of `through-space' and `through-bond' interactions using binuclear complexes to model the three copper(II) polymers. Three conclusions can be drawn from the orbital interaction analysis: (1) in the first polymer, a superexchange pathway is formed with the bond of Cu–-N and the through-bond interaction between the lone pairs of the nitrogen atoms of pyrazine will lead to an antiferromagnet state; (2) in the second polymer a superexchange pathway is formed with the bond of Cu–-N and the through-space interaction between the lone pairs of the nitrogen atoms of pyrimidine, and as a result an antiferromagnetic state will be preferred; and (3) in the third polymer., there is no effective pathway in respect of overlap interaction and the HOMO and the LUMO are actually degenerate, and thus a ferromagnetic state will arise. The band structures are analyzed to characterize the magnetic properties of the antiferromagnetic polymers, [Cu(PZ)(NO3)2]n and [Cu(PM)(NO3)2(H2O)2], and the ferromagnetic polymer, [Cu(PM)2(NO3)2]n. 相似文献