排序方式： 共有5条查询结果，搜索用时 15 毫秒
1
1.
2.
李冕斌 《大学图书情报学刊》2012,30(3):14-16
文章叙述了海南省教育科研数字图书馆建设目标、发展模式、资源建设与服务工作,分析了其存在问题与不足,根据海南省高校和图书馆发展状况,就海南省教育科研数字图书馆＂总馆—分馆模式＂的机制研究、平台建设、学科文献信息中心建设、经费投入等方面提出建议与思考。 相似文献
3.
Jia-wei LOU Li ZHU Mian-bin WU Li-rong YANG Jian-ping LIN Pei-lin CEN 《Journal of Zhejiang University. Science. B》2014,15(5):491-499
The Rhodobacter capsulatus hemA gene, which encodes 5-aminolevulinic acid synthase (ALAS), was expressed in Escherichia coli Rosetta (DE3) and the enzymatic properties of the purified recombinant ALAS (RC-ALAS) were studied. Compared with ALASs encoded by hemA genes from Agrobacterium radiobacter (AR-ALAS) and Rhodobacter sphaeroides (RS-ALAS), the specific activity of RC-ALAS reached 198.2 U/mg, which was about 31.2% and 69.5% higher than those of AR-ALAS (151.1 U/mg) and RS-ALAS (116.9 U/mg), respectively. The optimum pH values and temperatures of the three above mentioned enzymes were all pH 7.5 and 37 °C, respectively. Moreover, RC-ALAS was more sensitive to pH, while the other two were sensitive to temperature. The effects of metals, ethylene diamine tetraacetic acid (EDTA), and sodium dodecyl sulfate (SDS) on the three ALASs were also investigated. The results indicate that they had the same effects on the activities of the three ALASs. SDS and metal ions such as Co2+, Zn2+, and Cu2+ strongly inhibited the activities of the ALASs, while Mn2+ exerted slight inhibition, and K+, Ca2+, Ba2+, Mg2+, or EDTA had no significant effect. The specificity constant of succinyl coenzyme A [(k cat/K m)S-CoA] of RC-ALAS was 1.4989, which was higher than those of AR-ALAS (0.7456) and RS-ALAS (1.1699), showing its high catalytic efficiency. The fed-batch fermentation was conducted using the recombinant strain containing the R. capsulatus hemA gene, and the yield of 5-aminolevulinic acid (ALA) achieved was 8.8 g/L (67 mmol/L) under the appropriate conditions. 相似文献
4.
Hua CHEN Mian-bin WU Zheng-jie CHEN Ming-lu WANG Jian-ping LIN Li-rong YANG 《Journal of Zhejiang University. Science. B》2013,14(4):346-354
A 24-membered ring macrolide compound,macrolactin A has potential applications in pharmaceuticals for its anti-infectious and antiviral activity.In this study,macrolactin A was produced by a marine bacterium,which was identified as Bacillus subtilis by 16S ribosomal RNA(rRNA) sequence analysis.Electrospray ionization mass spectrometry(ESI/MS) and nuclear magnetic resonance(NMR) spectroscopy analyses were used to characterize this compound.To improve the production,response surface methodology(RSM) involving Box-Behnken design(BBD) was employed.Faeces bombycis,the main by-product in sericulture,was used as a nitrogen source in fermentation.The interactions between three significant factors,F.bombycis,soluble starch,and(NH4)2SO4 were investigated.A quadratic model was constructed to fit the production and the factors.Optimum medium composition was obtained by analysis of the model.When cultivated in the optimum medium,the production of macrolactin A was increased to 851 mg/L,2.7 times as compared to the original.This study is also useful to find another way in utilizing F.bombycis. 相似文献
5.
Jia-wei LOU Li ZHU Mian-bin WU Li-rong YANG Jian-ping LIN Pei-lin CEN 《Journal of Zhejiang University. Science. B》2014,(5)
研究目的:提供一种酶学性质优良的,可在大肠杆菌体内高活性可溶表达的,具有工业应用前景的5-氨基乙酰丙酸合成酶。创新要点:利用E.coli Rosetta(DE3)表达编码荚膜红细菌5-氨基乙酰丙酸合成酶(RC-ALAS)的hemA基因,实现其在大肠杆菌体内高活性可溶表达。以放射形土壤杆菌和类球红细菌hemA基因表达的5-氨基乙酰丙酸合成酶(AR-ALAS和RS-ALAS)为参照,对分离纯化后的RC-ALAS进行酶学性质对比研究。研究方法:工程菌的构建如图1所示,酶的分离纯化采用镍柱亲和层析和凝胶过滤层析,酶学性质的测定采用对比研究法。重要结论:(1)RC-ALAS酶活性高达198.2 U/mg,比AR-ALAS(151.1 U/mg)和RS-ALAS(116.9 U/mg)分别提高31.2%和69.5%;(2)RC-ALAS对底物琥珀酰辅酶A的专一性常数((kcat/Km)S-CoA)为1.4989,高于AR-ALAS(0.7456)和RS-ALAS(1.1699),具有较高的催化效率;(3)对含有荚膜红细菌hemA基因的工程菌进行补料分批发酵,发酵结束时,ALA的产量高达8.8 g/L(67 mmol/L)。 相似文献
1