• Title, Summary, Keyword: thermostability

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Increase of the Thermostability of Cyclodextrin Glucanotransferase (Cyclodextrin Glucanotransferase의 열안정성 증가)

  • 김진현;홍승서;이현수
    • KSBB Journal
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    • v.16 no.2
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    • pp.212-215
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    • 2001
  • The effect of various additives on the thermostability of Bacillus sp. cyclodextrin glucanotransferase (CGTase) was investigated. CaCl$_2$, starch, and glycerol had a positive effect on the thermostability of the CGTase, which was very stable for 6 months with added starch (5%, w/v) and CaCl$_2$(0.05 M) at 30$^{\circ}C$.

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Thermostability of Chimeric Cytidine Deaminase Variants Produced by DNA Shuffling

  • Park, Yu-Mi;Phi, Quyet Tien;Song, Bang-Ho;Ghim, Sa-Youl
    • Journal of Microbiology and Biotechnology
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    • v.19 no.12
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    • pp.1536-1541
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    • 2009
  • The DNA shuffling technique has been used to generate libraries of evolved enzymes in thermostability. We have shuffled two thermostable cytidine deaminases (CDAs) from Bacillus caldolyticus DSM405 (T53) and B. stearothermophilus IFO12550 (T101). The shuffled CDA library (SH1067 and SH1077 from the first round and SH2426 and SH2429 from the second round) showed various patterns in thermostability. The CDAs of SH1067 and SH1077 were more thermostable than that of T53. SH2426 showed 150% increased halftime than that of T53 at $70^{\circ}C$. The CDA of SH2429 showed about 200% decreased thermostability than that of T53 at $70^{\circ}C$. A single amino acid residue replacement that presented between SH1077 and SH2429 contributed to dramatic changes in specific activity and thermostability. On SDS-PAGE, the purified CDA of SH1077 tetramerized, whereas that of SH2429 denatured and became almost monomeric at $80^{\circ}C$. A simulated three-dimensional structure for the mutant CDA was used to interpret the mutational effect.

Effect of Various Additives and Solvents on Thermostability of Cyclodextrin Glucanotransferase from Bacillus stearothermophilus (여러 첨가물의 용매가 Bacillus stearothermophilus가 생산하는 Cyclodextrin Glucanotransferase의 열안정성에 미치는 영향)

  • 안중훈;황진봉;김승호
    • Microbiology and Biotechnology Letters
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    • v.19 no.4
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    • pp.368-371
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    • 1991
  • The influence of ethylene glycol, glycerol, sorbitol and sucrose on the thermostability of Bacilus stearothermophzlus cyclodextrin glucanotransferase (CGTase) was investigated. Glycerol, sorbitol and sucrose had effect on thermostability of the CGTase. The effects appeared to be strongly dependent on concentration of additives. The thermostability of CGTase also was assayed in organic solvents such as n-butanol, l, &dioxane, n-octane. The therrnostability of CGTase increased in l, 4-dioxane and n-octane. Particularly, in n-octane, the CGTase retained the 81% of the initial activity after incubation at $75^{\circ}C$ for 90 min.

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Thermostability of Polyphenol Oxidase from Potato (Solanum tuberosum L.) (감자 Polyphenol Oxidase의 열안정성)

  • 김나영;이민경;박인식;방극승;김석환
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.30 no.5
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    • pp.844-847
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    • 2001
  • Factors affecting thermostability of polyphenol oxidase (PPO) from potato were studied for the purpose of providing useful information for food processing operations. The enzyme was most stable at pH 7.0 and it was inhibited to 70% after heat treatment at 8$0^{\circ}C$ for 1 min. The z-value for the thermal inactivation of the PPO was 12.17$\pm$0.58$^{\circ}C$. The thermostability of the enzyme was reduced by addition of sodium chloride. And the activity was inhibited by addition of reducing reagents such as 2-mercaptoethanol and dithiothreitol.

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Thermostability and Reactivation of Peroxidase from Soybean Sprouts (콩나물 Peroxidase의 열안정성과 재활성화)

  • 박인식;이민경;길지은
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.28 no.1
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    • pp.81-86
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    • 1999
  • The factors affecting thermostability and reactivation of peroxidase from soybean sprouts(Glycine max L.) were investigated. The enzyme was the most stable at pH 7.0 and below 60oC. Thermostability of the enzyme was reduced by addition of sodium chloride and saccharides. The partially inactivated enzyme by heat treatment at 75oC for 10 min was reactivated up to 211.5% at the optimal reactivation condition. The optimal pH and temperature for reactivation of the enzyme were pH 9.0 and 40oC, respectively. The reactivation was completely inhibited by addition of sulfhydryl reagent such as L cysteine.

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Heat sensitivity on physiological and biochemical traits in chickpea (Cicer arietinum)

  • Jain, Amit Kumar
    • Advances in environmental research
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    • v.3 no.4
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    • pp.307-319
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    • 2014
  • Four chickpea cultivars viz. kabuli (Pusa 1088 and Pusa 1053) and desi (Pusa 1103 and Pusa 547) differing in sensitivity to high temperature conditions were analyzed in earthern pot (30 cm) at different stages of growth and development in the year of 2010 and 2011. Pusa-1053 (kabuli type) showed maximum photosynthetic rate and least by Pusa-547 (desi type), whereas maximum cell membrane thermostability were recorded in Pusa-1103 and minimum in Pusa-1088. Among the treatments, the plants grown under elevated temperature conditions had produced 13.01% more significant data in comparison to plants grown under continuous natural conditions. Stomatal conductance were reduced 44.25% under elevated temperature conditions than natural conditions, whereas 35.56%, when plants grown under initially natural conditions upto 30DAS, then 30-60DAS elevated temperature and finally shifted to natural conditions till harvest. In case of Pusa-1103, stomatal conductance was maximum as compared to rest of 2.7% from Pusa-1053, 8.9% from Pusa-1088, and 10.3% in Pusa-547 throughout the study. Plants grown under continuous elevated temperature conditions had produced 15.30% and 15.32% more significant membrane thermostability index in comparison to continuous natural conditions at vegetative stage and 19.40% and 18.44% at flowering stage, while the better response was recorded at pod formation stage. Pusa-1053 had given 2.8% more membrane thermostability index than Pusa-1088 and Pusa-1103 had given 1.6% more membrane thermostability index than Pusa-547 in the present study. The membrane disruption caused by high temperature may alter water ion and inorganic solutes movement, photosynthesis and respiration. Thus, thermostability of the cell membrane depends on the degree of the electrolyte leakage.

Thermoanaerobacter ethanolicus Amylopullulanase Thermophilicity와 Thermostability의 Molecular Analysis

  • Park, Jong-Hyeon
    • Bulletin of Food Technology
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    • v.8 no.4
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    • pp.179-191
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    • 1995
  • Thermoanaerobacter ethanolicus유래 thermophilic amylopullulanase의 thermophilicity와 thermostability의 기작을 규명하기 위하여 N-말단과 C-말단으로부터 nested deletion mutatnt와 sitedirected mutagenesis등에 의한 변이효소를 제조, 분석하였다. 이러한 까다로운 변이효소를 제조하여 amylopullulanase의 특정부위가 효소의 thermophilicity와 thermostability에 관여하고 있는 것을 확인했다. N-말단의 start amino acid에서 194와 324 아미노산잔기에 이르는 부위 (TPR)가 이 효소의 높은 최적반응온도의 유지에 관련되어 있고 1102와 1224잔기에 이르는 부위 (TSR)는 thermodenaturation이 잘 일어나지 않도록 하고 있었다. 야생형 amylopullulanase (Apu), 변이효소중 ApuN342와 ApuN106/C379는 비슷한 효소비활성과 Km값을 가지고 있었다. TPR부위의 site-directed mutagenesis에 의한 변이효소중 P240A (proline$\rightarrow$alanine), P244A, P240A-P244A는 야생형의 최적반응온도 $80^{\circ}C$와 똑같았지만 효소의 열안전성(반감기)는 $85^{\circ}C$에서 21, 105, 128분을 보여 주었다. TSR에서의 변이효소중 P1159A, P1202A는 열안전성은 비슷하였지만 반응최적온도는 $85^{\circ}C$$90^{\circ}C$로 야생형 Apu보다 오히려 높아졌다. 따라서 proline은 분자내에서 thermophilicity와 thermostability를 항상 증가시키는 쪽으로 영향을 주지 않는 것으로 보인다. Proline은 그 위치와 주위의 다른 아미노산잔기와 같이 종합적으로 분자의 구조에 영향을 미치고 있는 것으로 판단된다.

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Thermostability of Monolithic and Reinforced Al-Fe-V-Si Materials

  • He, Yiqiang;Qiao, Bin;Wang, Na;Yang, Jianming;Xu, Zhengkun;Chen, Zhenhua;Chen, Zhigang
    • Advanced Composite Materials
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    • v.18 no.4
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    • pp.339-350
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    • 2009
  • Al-Fe-V-Si alloys reinforced with SiC particles were prepared by multi-layer spray deposition technique. Both microstructures and mechanical properties including hardness and tensile properties development during hot exposure process of Al-8.5Fe-1.3V-1.7Si, Al-8.5Fe-1.3V-1.7Si/15 vol% $SiC_P$ and Al-10.0Fe-1.3V-2Si/15 vol% $SiC_P$ were investigated. The experimental results showed that an amorphous interface of about 3 nm in thickness formed between SiC particles and the matrix. SiC particles injected silicon into the matrix; thus an elevated silicon concentration was found around $\alpha-Al_{12}(Fe,\;V)_3Si$ dispersoids, which subsequently inhibited the coarsening and decomposition of $\alpha-Al_{12}(Fe,\;V)_3Si$ dispersoids and enhanced the thermostability of the alloy matrix. Moreover, the thermostability of microstructure and mechanical properties of Al-10.0Fe-1.3V-2Si/15 vol% $SiC_P$ are of higher quality than those of Al-8.5Fe-1.3V-1.7Si/15 vol% $SiC_P$.

Studies on the Thermostability of Myofibrillar Proteins of Mollusca (연체류의 근원섬유단백질에 열 안정성에 관한 연구)

  • 신완철;송재철;김영호
    • The Korean Journal of Food And Nutrition
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    • v.10 no.2
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    • pp.160-165
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    • 1997
  • The actomyosin and myosin of the squid at 3$0^{\circ}C$ showed the highest Vmax and the actomyosin and myosin of the clam at 35$^{\circ}C$ and HMM at $25^{\circ}C$ showed the highest Vmax the thermostability of myofibrillar proteins is changed greatly according to the difference of KCI concentration. The myofibrillar proteins of the clam showed a higher thermostability than the myofibrillar proteins of the squid. When 3% ethanol solution was added and heated myofibrillar proteins, denaturation was accelerated and it was shown that there was a difference between animals in the denaturation velocity.

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A Novel Strategy for Thermostability Improvement of Trypsin Based on N-Glycosylation within the Ω-Loop Region

  • Guo, Chao;Liu, Ye;Yu, Haoran;Du, Kun;Gan, Yiru;Huang, He
    • Journal of Microbiology and Biotechnology
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    • v.26 no.7
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    • pp.1163-1172
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    • 2016
  • The Ω-loop is a nonregular and flexible structure that plays an important role in molecular recognition, protein folding, and thermostability. In the present study, molecular dynamics simulation was carried out to assess the molecular stability and flexibility profile of the porcine trypsin structures. Two Ω-Loops (fragment 57-67 and fragment 78-91) were confirmed to represent the flexible region. Subsequently, glycosylation site-directed mutations (A73S, N84S, and R104S) were introduced within the Ω-loop region and its wing chain based on its potential N-glycosylation sites (Asn-Xaa-Ser/Thr consensus sequences) and structure information to improve the thermostability of trypsin. The result demonstrated that the half-life of the N84S mutant at 50℃ increased by 177.89 min when compared with that of the wild-type enzyme. Furthermore, the significant increase in the thermal stability of the N84S mutant has also been proven by an increase in the Tm values determined by circular dichroism. Additionally, the optimum temperatures of the wild-type enzyme and the N84S mutant were 75℃ and 80℃, respectively. In conclusion, we obtained the thermostability-improved enzyme N84S mutant, and the strategy used to design this mutant based on its structural information and N-linked glycosylation modification could be applied to engineer other enzymes to meet the needs of the biotechnological industry.