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Molecular identification and enzymatic properties of laccase2 from the diamondback moth Plutella xylostella (Lepidoptera:Plutellidae)

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Journal of Integrative Agriculture 2018年第10期17卷 2310-2319页

作者： LIU Zhen-gang WANG Huan-huan XUE Chao-bin Key Laboratory of Pesticide Toxicology and Application Technique College of Plant Protection Shandong Agricultural University

Laccase（EC 1.***.3.2）is known to oxidize various aromatic and nonaromatic compounds via a radical-catalyzed reaction,which generally includes two types of laccase,Lac1 and ***1 oxidizes toxic compounds in the diet,and Lac2 is known to play an important role in melanizing the insect *** this study,we cloned and sequenced the cDNA of the diamondback moth,Plutella xylostella Lac2（PxLac2）,from the third instar larvae using polymerase chain reaction（PCR）and rapid amplification of cDNA ends *** results showed that the full-length PxLac2 cDNA was 1 944 bp long and had an open reading frame of 1 794 ***2 encoded a protein with 597 amino acids and had a molecular weight of 66.09 ***,we determined the expression levels of PxLac2 in different stages by quantitative PCR（qPCR）.The results indicated that PxLac2 was expressed differently in different *** observed the highest expression level in pupae and the lowest expression level in fourth instar *** also investigated the enzymatic properties of laccase,which had optimal activity at pH 3.0 and at 35°*** these optimal conditions,laccase had a Michaelis constant（Km）of 0.97 mmol L-1,maximal reaction speed（Vm）of 56.82 U mL-1,and activation energy（Ea）of 17.36 kJ mol-1 to oxidize2,2＇-azino-bis（3-ethylbenzothiazoline-6-sulfonic acid ammonium salt）.Type II copper enhanced laccase activity below 0.8mmol L-1 and reduced enzyme activity above 0.8 mmol L-1 with an IC50 concentration of 1.26 mmol *** study provides insights into the biological function of laccase.

关键词： laccase melanization in vivo expression enzymatic properties Plutella xylostella

High-level soluble expression of the hemA gene from Rhodobacter capsulatus and comparative study of its enzymatic properties

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2014年第5期15卷 491-499页

作者： Jia-wei LOU Li ZHU Mian-bin WU Li-rong YANG Jian-ping LIN Pei-lin CEN Key Laboratory of Biomass Chemical Engineering of Ministry of Education Department of Chemical and Biological EngineeringZhejiang University

The Rhodobacter capsulatus hemA gene, which encodes 5-aminolevulinic acid synthase （ALAS）, was expressed in Escherichia coil 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 ℃, 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 Co^2＋, Zn^2＋, and Cu^2＋ strongly inhibited the activities of the ALASs, while Mn^2＋ exerted slight inhibition, and K^＋, Ca^2＋, Ba^2＋, Mg^2＋, or EDTA had no significant effect. The specificity constant of succinyl coenzyme A [（kcatlKm）^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.

关键词： 5-Aminolevulinic acid Rhodobacter capsulatus High-level expression enzymatic properties

Mutagenesis of Alkaline Protease-Producing Marine Strains and enzymatic properties

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Agricultural Biotechnology 2012年第2期1卷 32-34,37页

作者： Wei XIA Hua LI Xiaoli WANG Guoyu ZHANG Chao LI Shaohui ZHU Hao ZHANG Quanhan XU Qingdao Zhongren Pharmaceutical Co. Ltd.

[ Objective] The aim of the research was to select alkaline pmtease-producing strains and provide basis for the application in production. [ Method ] An alkaline protease-preducing strain was isolated from the sea water and sea mud collected from Qingdao coastal area. After ultraviolet mutagenesis and microwave mutagenesis, a target strain ZR-58-3-1-3 was obtained. The protease activity and enzymatic properties of the strain were determined preliminarily. [ Result ] Prote- ase activity of the selected strain reached 145 U/ml. After the compound mutagenesis, protease activity of the fermentation liquid of strain ZR-58-3-1-3 reached 775 U/m｜, which was about 4.3 times higher than that of the original strain. The optimal temperature for alkaline protease produced by strain ZR-58-3-1-3 was 45℃, and the optimal pH was 8.5, suggesting it belongs to moderate temperature protease with relatively high thermal stabihty. [ Conclusion] Strain ZR-58-3-1-3 has stable alkaline protease production performance and can be used as an alkaline protease-producing mutant strain.

关键词： Alkaline protease Marine strain Mutagenesis enzymatic properties

Isolating and Screening of Effective Decomposing Strain of Silkworm Chrysalis Protein and Study on Parts of Its enzymatic properties

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Agricultural Science & Technology 2010年第2期11卷 8-11页

作者：孔军涂国全邝哲师赵祥杰叶明强罗国庆广东省农业科学院农业生物技术研究所广东广州510610 江西农业大学生物科学与工程学院江西南昌330045

[Objective] The research aimed to obtain an effectively-decomposing strain of silkworm chrysalis protein and discuss its enzymatic properties.[Method] The effectively-decomposing bacteria of protein was isolated from the decayed silkworm chrysalis by using dilution plate and its enzymatic properties were tested after primary screening and second *** enzyme activity was determined and the intermediate and small molecule protein content in silkworm chrysalis was measured after solid-state fermentati...

关键词： Decomposing strain of silkworm chrysalis Isolating and screening Neutral protease enzymatic properties

Studies on the Isolation and Screening of α-amylase Producing Strain and Their enzymatic properties

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Agricultural Science & Technology 2010年第7期11卷 56-58,90页

作者：刘雅琴陈海魁李瑞雪北方民族大学生物科学与工程学院宁夏银川750021

[Objective] The aim was to obtain α-amylase producing strains with some excellent properties like high temperature resistance,strong acid resistance,strong alkali resistance,etc..[Method] α-amylase producing strains were isolated and screened; furthermore their enzymatic properties were studied.[Result] 10 strains with an obvious starch hydrolysis cycle were screened out from starch screening plate coated by diluted sample,from which 3 strains with higher α-amylase activity were screened out,that was X6,X8 and *** for X6,X8 and X10,their optimum pH values all belonged to neutral,and their optimum temperatures were all 60 ℃.Meanwhile,Ca^2＋ could increase their enzyme thermal *** the concentration of Ca^2＋ was 0.02-0.04 mol/L,the enzyme thermal stability of X6 and X8 reached the highest; When the concentration of Ca^2＋ was 0.03-0.04 mol/L,that of X10 reached the highest; When the concentration of Ca^2＋ was increased continuously,those of the 3 strains all decreased.[Conclusion] The research provides theoretical basis for satisfying the demands of different industries for α-amylase with different characteristics.

关键词： α-amylase Isolation enzymatic properties

Characterization of putative mannoprotein in Kluyveromyces lactis for lactase production

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Synthetic and Systems Biotechnology 2023年第1期8卷 168-175页

作者： Xiuru Shen Lingtong Liao Guoqiang Zhang Jingwen Zhou Jianghua Li Guocheng Du Science Center for Future Foods Jiangnan UniversityWuxi214122China National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing Jiangnan University1800 Lihu RoadWuxiJiangsu214122China School of Biotechnology and Key Laboratory of Industrial Biotechnology Ministry of EducationJiangnan University1800 Lihu RoadWuxiJiangsu214122China

Lactase is a member of theβ-galactosidase family of enzymes that can hydrolyze lactose into galactose and ***,extracellular lactase production was still restricted to the process of cell *** this study,lactase-producing Kluyveromyces lactis JNXR-2101 was obtained using a rapid and sensitive method based on the fluorescent substrate 4-methylumbelliferyl-β-*** purified enzyme was identified as a neutral lactase with an optimum pH of *** facilitate extracellular production of lactase,a putative mannoprotein KLLA0_E01057g of *** was knocked *** could effectively promote cell wall degradation and lactase production after lyticase treatment,which showed potential on other extracellular enzyme *** optimizing the fermentation conditions,the lactase yield from mannoprotein-deficient *** JNXR-2101ΔE01057g reached 159.62 U/mL in a 5-L fed-batch bioreactor.

关键词： Kluyveromyces lactis Lactase Screening enzymatic properties Mannoprotein Fermentation optimization Secretion

Characterization of a Novel Esterase Belonging to Family V from Marinobacter flavimaris

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Journal of Ocean University of China 2024年第1期23卷 221-232页

作者： HE Jingjing ZHANG Yunhui WU Leilei WANG Yaru ZHANG He LIU Zhengang SHI Xiaochong Frontiers Science Center for Deep Ocean Multispheres and Earth System and College of Marine Life SciencesOcean University of ChinaQingdao 266003China Laboratory for Marine Ecology and Environmental Science Laoshan LaboratoryQingdao 266237China Institute of Evolution&Marine Biodiversity Ocean University of ChinaQingdao 266003China

Lipolytic enzymes have attracted enormous attentions because of their ability in ester hydrolysis,ester synthesis,transesterification and other biochemical *** are important sources of lipolytic enzymes applied in ***,a novel lipolytic enzyme encoded by esterase gene est1347 was identified in Marinobacter flavimaris WLL162,and was purified and *** lipolytic enzyme Est1347 consisted of 312 amino acid residues and a 21-amino-acids N-terminal signal peptide with a predicted molecular weight of 34.2 *** belongs to family V of bacterial lipolytic enzymes based on the amino acid sequence homology ***1347 is a mesophilic and alkali-resistant enzyme with the highest activity at 45℃and pH 8.5;it is stable at temperatures below 50℃and pH 7.5–***1347 showed a preference for middle-length chain substrate p-NPC10 and a wide range of other *** Km,Vmax,Kcat and Kcat/Km values of Est1347 for p-NPC10 in pH 8.5 at 45℃were 0.9411 mmol L^(−1),1285μmol min^(−1)mg^(−1),698.91 s^(−1)and 743.65 s^(−1)(mmol L^(−1))^(−1),*** is also tolerant to the metal ions,organic solvents and *** conclusion,the esterase Est1347 laid a foundation for further study of bacterial lipolytic enzyme family V.

关键词： esterase Marinobacter flavimaris enzymatic properties lipolytic enzyme family V

Human lactate dehydrogenase and malate dehydrogenase possess the catalytic properties to produce aromatic α‑hydroxy acid

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Systems Microbiology and Biomanufacturing 2023年第4期3卷 627-633页

作者： Litong Wang Tai‑Ping Fan Mei Wang Yajun Bai Xiaohui Zheng Yujie Cai The Key Laboratory of Industrial Biotechnology Ministry of EducationSchool of BiotechnologyJiangnan University1800 Lihu RoadWuxi 214122JiangsuChina Department of Pharmacology University of CambridgeCambridge CB21TUK Leiden University‑European Center for Chinese Medicine and Natural Compounds Institute of BiologyLeiden UniversitySylviusweg 722333BE LeidenThe Netherlands College of Life Sciences Northwest UniversityXi’an 710069ShanxiChina

Lactate dehydrogenase and malate dehydrogenase are the two main alpha-hydroxy acid dehydrogenases in the human *** investigated the catalytic properties of human lactate dehydrogenase LDHC,LDHL6A and malate dehydrogenase MDH1 on aromatic α-keto acids phenylpyruvic acid,p-hydroxyphenylpyruvic acid and 3,4-dihydroxyphenylpyruvic *** optimum temperatures for LDHC,LDHL6A,and MDH1 are 37℃,35℃,and 45℃,respectively;and the optimum pH is 6.5,6.5,and 5.5,*** K_(m)of LDHC for phenylpyruvic acid and 3,4-dihydroxyphenylpyruvic acid were 0.90 mM and 0.92 mM,***6A has a high affinity for phenylpyruvic acid and 3,4-dihydroxyphenylpyruvic acid with K_(m)of 0.77 mM and 0.80 mM,respectively;MDH1 has an extremely high affinity(K_(m)=0.46 mM)and catalytic efficiency(k_(cat)/K_(m)=23.87 s^(-1)·mM^(-1))for p-hydroxyphenylpyruvic *** also has a high affinity for 3,4-dihydroxyphenylpyruvic acid with a K_(m)of 0.90 mM,but with a low affinity for phenylpyruvic acid(K_(m)=3.76 mM).The catalytic properties of human LDHC,LDHL6A,and MDH1 for the abovementioned aromatic α-keto acids may be one of the sources of L-phenyllactic acid,L-p-hydroxyphenyllactic acid,and L-3,4-dihydroxyphenyllactic acid in humans.

关键词： Aromaticα-keto acids Lactate dehydrogenase Malate dehydrogenase L-phenyllactic acid enzymatic properties

Purification and Characterization of a Versatile Peroxidase from Edible Mushroom Pleurotus eryngii

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Chinese Journal of Chemical Engineering 2010年第5期18卷 824-829页

作者：陈敏姚善泾张虹梁新乐 Department of Chemical and Biochemical Engineering Zhejiang University Hangzhou 310027 China Deigartment of Biotechnology Engineering Zhejiang Gongshang University Hangzhou 310012 China

A versatile peroxidase (VP-Peco60-7 ) was generated and purified from the liquid culture of Pleurotus eryngii. The purification procedure included ammonium sulfate precipitation, ion exchange chromatography, and gel chromatography. The molecular weight and isoelectric point (pI) of VP-Peco60-7 were determined to be approxi-mately 40 kDa and 4.1, respectively. By N-terminal sequence determination and peptide mapping analysis, VP-Peco60-7 was found to be similar to the versatile peroxidase isoenzyme VPL1, which was previously isolated from liquid cultures of the same species. However, the molecular weight and pI of VP-Peco60-7 were different from those of versatile peroxidases of liquid cultures, implying that the VP-Peco60-7 in this study is of a novel type. With 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) as a substrate, the maximal enzyme activity was obtained at 50 °C and pH 3.0. The catalysis of ABTS by VP-Peco60-7 was expressed by the Michaelis-Menten equa-tion. At 50 °C and pH 3.0, the maximum velocity (V max ) was 188.68 U·mg-1 and the michaelis constant (K m ) was 203.09 μmol·L-1 .

关键词： Pleurotus eryngii versatile peroxidase purification enzymatic properties