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931.
932.
Changling Zhang Haifeng Pan Lingli Yao Wenna Bao Jinxin Wang Zhipeng Xie Jianguo Zhang 《Biotechnology letters》2016,38(8):1301-1306
Objectives
To enhance activity of cis-epoxysuccinate hydrolase from Klebsiella sp. BK-58 for converting cis-epoxysuccinate to tartrate.Results
By semi-saturation mutagenesis, all the mutants of the six important conserved residues almost completely lost activity. Then random mutation by error-prone PCR and high throughput screening were further performed to screen higher activity enzyme. We obtained a positive mutant F10D after screening 6000 mutations. Saturation mutagenesis on residues Phe10 showed that most of mutants exhibited higher activity than the wild-type, and the highest mutant was F10Q with activity of 812 U mg?1 (k cat /K m , 9.8 ± 0.1 mM?1 s?1), which was 230 % higher than that of wild-type enzyme 355 U mg?1 (k cat /K m , 5.3 ± 0.1 mM?1 s?1). However, the thermostability of the mutant F10Q slightly decreased.Conclusions
The catalytic activity of a cis-epoxysuccinate hydrolase was efficient improved by a single mutation F10Q and Phe10 might play an important role in the catalysis.933.
Mohamed Elshikh Syed Ahmed Scott Funston Paul Dunlop Mark McGaw Roger Marchant Ibrahim M. Banat 《Biotechnology letters》2016,38(6):1015-1019
Objectives
To develop and validate a microdilution method for measuring the minimum inhibitory concentration (MIC) of biosurfactants.Results
A standardized microdilution method including resazurin dye has been developed for measuring the MIC of biosurfactants and its validity was established through the replication of tetracycline and gentamicin MIC determination with standard bacterial strains.Conclusion
This new method allows the generation of accurate MIC measurements, whilst overcoming critical issues related to colour and solubility which may interfere with growth measurements for many types of biosurfactant extracts.934.
Wojciech Barczak Pawel Golusiński Lukasz Luczewski Wiktoria M. Suchorska Michal M. Masternak Wojciech Golusiński 《Biotechnology letters》2016,38(10):1665-1672
Head and neck squamous cell carcinoma is the sixth leading cause of cancer worldwide. The most common risk factors are carcinogens (tobacco, alcohol), and infection of the human papilloma virus. Surgery is still considered as the treatment of choice in case of head and neck cancer, followed by a reconstructive surgery to enhance the quality of life in the patients. However, the widespread use of artificial implants does not provide appropriate physiological activities and often cannot act as a long-term solution for the patients. Here we review the applicability of multiple stem cell types for tissue engineering of cartilage, trachea, vocal folds and nerves for head and neck injuries. The ability of the cells to self-renew and maintain their pluripotency state makes them an attractive tool in tissue engineering. 相似文献
935.
Zhiqiang Zhao Hualei Wang Yiping Zhang Lifeng Chen Kai Wu Dongzhi Wei 《Biotechnology letters》2016,38(10):1799-1808
Objectives
To discover novel ketoreductases (KRED) from soil metagenome preparation of chiral alcohols.Results
Three putative KRED were cloned, heterologously expressed in Eschericha coli and characterized based on the sequence analysis of soil metagenome. All the three enzymes (KRED424, KRED432, and KRED433) had maximum activity at 55 °C and pH 7. KRED424 had a broader substrate spectrum compared with the other two. Three prochiral carbonyl compounds were used to evaluate the abilities of enantioselective reductions of the KRED. For N-Boc-3-pyrrolidone, all enzymes produced an (S)-type alcohol in enantiomeric excess (>99 % ee). For ethyl 2-oxo-4-phenylbutyrate, KRED424 showed a higher conversion (91.5 %) and enantioselectivity (S-type, >99 % ee) than KRED432 and KRED433. For ethyl 4-chloroacetoacetate (COBE), both of KRED424 and KRED433 completely converted 20 mM substrate and KRED433 could obtain an (R)-alcohol with 94 % ee.Conclusions
The three ketoreductases have potential in the preparation of pharmaceuticals and fine chemicals.936.
Wen-Jie Fan He-Ping Li He-Shui Zhu Shi-Ping Sui Pei-Ge Chen Yue Deng Tong-Ming Sui Yue-Ying Wang 《Biotechnology letters》2016,38(11):1839-1849
Objectives
To determine the effect of NF-κB on cell proliferation and apoptosis, we investigate the expression of inflammation and apoptosis-related factors in the bovine mammary epithelial cell line, MAC-T.Results
MAC-T cells were cultured in vitro and MTT and LDH assays used to determine the effects of lipopolysaccharide (LPS) on proliferation and cytotoxicity respectively. RT-PCR and western blotting were used to evaluate the effect of LPS and NF-κB inhibition [pyrrolidine dithiocarbamate (PDTC) treatment] on the expression of inflammation and apoptosis-related factors. LPS significantly inhibited MAC-T cell proliferation in a dose- and time-dependent manner. Furthermore, LPS promoted apoptosis while the NF-кB inhibitor PDTC attenuated this effect. After LPS treatment, the NF-кB signaling pathway was activated, and the expression of inflammation and apoptosis-related factors increased. When PDTC blocked NF-кB signaling, the expression of inflammation and apoptosis-related factors were decreased in MAC-T cells.Conclusions
LPS activates the TLR4/NF-κB signaling pathway, inhibits proliferation and promotes apoptosis in MAC-T cells. NF-кB inhibition attenuates MAC-T cell apoptosis and TLR4/NF-κB signaling pathway. NF-кB inhibitor alleviating MAC-T cell apoptosis is presumably modulated by NF-кB.937.
Objectives
To improve the stability and sweetness of the sweet-tasting protein, monellin, by using site-directed mutagenesis and a Pichia pastoris expression system with a GAPDH constitutive promoter.Results
Both wild-type and E2 N mutant of single-chain monellin gene were cloned into the PGAPZαA vector and expressed in Pichia pastoris. The majority of the secreted recombinant protein, at 0.15 g/l supernatant, was monellin. This was purified by Sephadex G50 chromatography. The sweetness threshold of wild-type and E2 N were 30 μg/ml and 20 μg/ml, respectively. Compared with the proteins expressed in Escherichia coli, the thermostability of both proteins was improved. The N-terminal sequence is determinative for the sweetness of the proteins expressed in yeast strains.Conclusions
Site-directed mutagenesis, modification of the N-terminus of monellin, and without the need of methanol induction in P. pastoris expression system, indicate the possibility for large-scale production of this sweet-tasting protein.938.
Xiaobo Dong Haiyun Li Yucheng Jiang Mancheng Hu Shuni Li Quanguo Zhai 《Biotechnology letters》2016,38(9):1483-1491
Objectives
To degrade enzymatically bisphenol A (BPA) that causes serious environmental concerns and is difficult to be degraded by chemical or physical methods.Results
BPA (150 mg l?1) was completely degraded by chloroperoxidase (CPO)/H2O2 within 7 min at room temperature, atmospheric pressure with the enzyme at 6 μg CPO ml?1. The degradation products were identified by HPLC–MS, which suggested involvement of multiple steps. Enzymatic treatment followed by existing bioremediation technologies (activated sludge) enhanced removal of COD from 9 to 54 %. Using an ecotoxicity evaluation with Chlorella pyrenoidosa, the degradation products had a lower toxicity than BPA.Conclusion
BPA can be degraded rapidly and efficiently under mild conditions with chloroperoxidase at 6 μg ml?1. The degradation products had a lower toxicity than BPA.939.
Long Jin Hai-Ying Zhu Qing Guo Xiao-Chen Li Yu-Chen Zhang Guang-Lei Zhang Xiao-Xu Xing Mei-Fu Xuan Qi-Rong Luo Xi-Jun Yin Jin-Dan Kang 《Biotechnology letters》2016,38(9):1433-1441
Objective
To examine the effect of PCI-24781 (abexinostat) on the blastocyst formation rate in pig somatic cell nuclear transferred (SCNT) embryos and acetylation levels of the histone H3 lysine 9 and histone H4 lysine 12.Results
Treatment with 0.5 nM PCI-24781 for 6 h significantly improved the development of cloned embryos, in comparison to the control group (25.3 vs. 10.5 %, P < 0.05). Furthermore, PCI-24781 treatment led to elevated acetylation of H3K9 and H4K12. TUNEL assay and Hoechst 33342 staining revealed that the percentage of apoptotic cells in blastocysts was significantly lower in PCI-24781-treated SCNT embryos than in untreated embryos. Also, PCI-24781-treated embryos were transferred into three surrogate sows, one of whom became pregnant and two fetuses developed.Conclusion
PCI-24781 improves nuclear reprogramming and the developmental potential of pig SCNT embryos.940.
Lifei Chen Chunling Ma Ruiming Wang Jianlou Yang Haijie Zheng 《Biotechnology letters》2016,38(10):1769-1774