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Wang, Yechun,Guo, Binhui,Zhang, Fei,Yao, Hongyan,Miao, Zhiqi,Tang, Kexuan Korean Society for Biochemistry and Molecular Biol 2007 Journal of biochemistry and molecular biology Vol.40 No.6
The enzyme 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR; EC1.1.1.34) catalyzes the first committed step of isoprenoids biosynthesis in MVA pathway. Here we report for the first time the cloning and characterization of a full-length cDNA encoding HMGR (designated as CgHMGR, GenBank accession number EF206343) from hazel (Corylus avellana L. Gasaway), a taxol-producing plant species. The full-length cDNA of CgHMGR was 2064 bp containing a 1704-bp ORF encoding 567 amino acids. Bioinformatic analyses revealed that the deduced CgHMGR had extensive homology with other plant HMGRs and contained two transmembrane domains and a catalytic domain. The predicted 3-D model of CgHMGR had a typical spatial structure of HMGRs. Southern blot analysis indicated that CgHMGR belonged to a small gene family. Expression analysis revealed that CgHMGR expressed high in roots, and low in leaves and stems, and the expression of CgHMGR could be up-regulated by methyl jasmonate (MeJA). The functional color assay in Escherichia coli showed that CgHMGR could accelerate the biosynthesis of $\beta$-carotene, indicating that CgHMGR encoded a functional protein. The cloning, characterization and functional analysis of CgHMGR gene will enable us to further understand the role of CgHMGR involved in taxol biosynthetic pathway in C. avellana at molecular level.
Yong Feng,Haoxiang Wang,Min Zhang,Zihao Zhu,Xiaoyu Wang,Binhui Jia,Xiaolin Jia 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.5
Titanium Matrix Composites (TMCs) are widely used in aerospace because of their excellent mechanical properties, but itis accompanied by the diffi culty of machining. Ultrasonic Vibration Assisted Drilling (UVAD) can eff ectively reduce theaxial force in the drilling process and improve the integrity of machined surface. In this paper, the discontinuous titaniummatrix composite TiBw/TC4 was developed by preparation method of in situ. In order to obtain the machining parameters ofTiBw/TC4 and guide the application of UVAD in TiBw/TC4, the contrast experiments between conventional drilling (CD)and UVAD were carried out to analyze the variation law of axial force. In this experiment, the frequency and amplitude ofultrasonic vibration were set as 35 kHz and 2.5 μm respectively, and the drilling conditions were that the spindle speed was(1500/1600/1700/1800/1900) r/min and the feed speed was (6/7/8/9/10) mm/min. The surface integrity of hole wall suchas roughness, residual stress and white layer was discussed. The experimental results show that the yield strength of TiBw/TC4 developed by in situ is 51% higher than that of pure TC4. Compared with CD, the axial force of TiBw/TC4 in UVADis signifi cantly reduced, and the formation of continuous chips and winding cutters is eff ectively reduced. Besides, the wearrate of the cutters is reduced. The number and size of hole wall defects, such as scratches, delamination and tearing, areobviously reduced. As well as the residual stress, white layer thickness and hole wall roughness are reduced by 4.67–16.31%,42.48% and 5.98–29.27% respectively. Within the limits of the experiment, when the spindle speed is 1700 r/min and thefeed speed is 8 mm/min, UVAD can obtain better hole wall surface integrity parameters.