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21.
Drepper T Raabe K Giaourakis D Gendrullis M Masepohl B Klipp W 《FEMS microbiology letters》2002,215(2):221-227
A novel esterase catalyzing regioselective hydrolysis was purified from the membrane fraction of Microbacterium sp. 7-1W, and characterized. The enzyme was solubilized with Brij 58 and purified 13.8-fold to apparent homogeneity with 2.58% overall recovery. The relative molecular mass of the native enzyme as estimated by gel filtration was more than 600,000 Da, and the subunit molecular mass was 62,000 Da. The enzyme catalyzed cleavage of the terminal ester bonds of cetraxate esters and pantothenate esters. The K(m) and V(max) values for methyl cetraxate were 0.380 mM and 7.76 micromole min(-1) mg(-1) protein, respectively. The enzyme was inhibited by serine hydrolase inhibitors. 相似文献
22.
Analysis of genetic effects of major genes and polygenes on quantitative traits I. Genetic model for diploid plants and animals 总被引:5,自引:0,他引:5
Lou XY Zhu J 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2002,104(2-3):414-421
A genetic model was proposed to simultaneously investigate genetic effects of both polygenes and several single genes for
quantitative traits of diploid plants and animals. Mixed linear model approaches were employed for statistical analysis. Based
on two mating designs, a full diallel cross and a modified diallel cross including F2, Monte Carlo simulations were conducted to evaluate the unbiasedness and efficiency of the estimation of generalized least
squares (GLS) and ordinary least squares (OLS) for fixed effects and of minimum norm quadratic unbiased estimation (MINQUE)
and Henderson III for variance components. Estimates of MINQUE (1) were unbiased and efficient in both reduced and full genetic
models. Henderson III could have a large bias when used to analyze the full genetic model. Simulation results also showed
that GLS and OLS were good methods to estimate fixed effects in the genetic models. Data on Drosophila melanogaster from Gilbert were used as a worked example to demonstrate the parameter estimation.
Received: 11 November 2000 / Accepted: 2 May 2001 相似文献
23.
An efficient screening method following UV mutagenesis yielded a high frequency of improved mutants of Trichosporon brassicae CGMCC 0574, a wild-type esterase-producer capable of enantioselectively hydrolyzing the ethyl ester of ketoprofen [2-(3-benzoylphenyl)
propionic acid]. The mutant had an activity 1.8-fold higher than the wild type and was stable in its enzyme production for
ten serial transfers. As the best single carbon source, isopropanol improved the specific activity of the enzyme 5-fold; and
this did not result from the effect of cell permeabilization. An 18-h culture grown on a medium containing 0.5% glucose plus
0.5% isopropanol produced 3-fold as much esterase as a culture grown on 1% glucose. 相似文献
24.
Heme proteins––hemoglobin and myoglobin possess esterase activities. Studies with purified hemoglobin from normal individuals
and diabetic patients revealed that the esterase activity as measured from hydrolysis of p-nitrophenyl acetate (p-NPA) was higher in diabetic condition and increased progressively with extent of the disease. HbA1c, the major glycated hemoglobin, which increases proportionately with blood glucose level in diabetes mellitus, exhibited
more esterase activity than the non-glycated hemoglobin fraction, HbA0, as demonstrated spectrophotometrically as well as by activity staining. Glycation influenced esterase activity of hemoglobin
by increasing the affinity for the substrate and the rate of the reaction. Both HbA0 and HbA1c-mediated catalysis of p-NPA hydrolysis was pH-dependent. Esterase activity of in vitro-glycated myoglobin (GMb) was also higher than that of its
non-glycated analog (Mb). The amplified esterase activities of hemoglobin and myoglobin might be associated with glycation-induced
structural modifications of the proteins. 相似文献
25.
Ping-Yi Li Xiu-Lan Chen Peng Ji Chun-Yang Li Peng Wang Yi Zhang Bin-Bin Xie Qi-Long Qin Hai-Nan Su Bai-Cheng Zhou Yu-Zhong Zhang Xi-Ying Zhang 《The Journal of biological chemistry》2015,290(17):11188-11198
Microbial hormone-sensitive lipases (HSLs) contain a CAP domain and a catalytic domain. However, it remains unclear how the CAP domain interacts with the catalytic domain to maintain the stability of microbial HSLs. Here, we isolated an HSL esterase, E40, from a marine sedimental metagenomic library. E40 exhibited the maximal activity at 45 °C and was quite thermolabile, with a half-life of only 2 min at 40 °C, which may be an adaptation of E40 to the permanently cold sediment environment. The structure of E40 was solved to study its thermolability. Structural analysis showed that E40 lacks the interdomain hydrophobic interactions between loop 1 of the CAP domain and α7 of the catalytic domain compared with its thermostable homologs. Mutational analysis showed that the introduction of hydrophobic residues Trp202 and Phe203 in α7 significantly improved E40 stability and that a further introduction of hydrophobic residues in loop 1 made E40 more thermostable because of the formation of interdomain hydrophobic interactions. Altogether, the results indicate that the absence of interdomain hydrophobic interactions between loop 1 and α7 leads to the thermolability of E40. In addition, a comparative analysis of the structures of E40 and other thermolabile and thermostable HSLs suggests that the interdomain hydrophobic interactions between loop 1 and α7 are a key element for the thermostability of microbial HSLs. Therefore, this study not only illustrates the structural element leading to the thermolability of E40 but also reveals a structural determinant for HSL thermostability. 相似文献
26.
Reina Wada Masanaru Ozaki Takashi Kumon Hiromichi Ohta 《Biocatalysis and Biotransformation》2015,33(3):188-190
A GGG(A)X-type esterase (Est0071) from an archaeon catalyzes asymmetric hydrolysis of prochiral bulky malonic diesters in good enantioselectivity. The selectivity of Est0071 was for the opposite enantiomer to that previously shown for pig liver esterase, and the resulting enantiomeric excess of the products was higher. Est0071 could also catalyze the hydrolysis of various acetates of secondary alcohols, and showed moderate enantioselectivity in these reactions. 相似文献
27.
An mRNA encoding the esterase from Alicyclobacillus acidocaldarius with catalytically essential serine codon (ACG) replaced by an amber (UAG) codon was used to study the suppression in in vitro translation system. Suppression of UAG by tRNA(Ser(CUA)) was monitored by determination of the full-length and active esterase. It was shown that commonly used increase of suppressor tRNA concentration inhibits protein production and therefore limits suppression. In situ deactivation of release factor by specific antibodies leads to efficient suppression already at low suppressor tRNA concentration and allows an in vitro synthesis of fully active enzyme in high yield undistinguishable from wild-type protein. 相似文献
28.
Sato S Nemoto M Kumazawa T Matsuba S Onodera J Aoyama M Obara H Kamada H 《Carbohydrate research》2004,339(14):2425-2432
N1-Acetoxy-2,2,6,6-tetramethylpiperidin-4-yl 2,3,4,6-tetra-O-benzyl-alpha- and -beta-D-glucopyranosides (3-alpha, beta) and N1-acetoxy-2,2,5,5-tetramethylpyrrolin-3-oyl 2,3,4,6-tetra-O-benzyl-alpha- and -beta-D-glucopyranosylamines (9-alpha, beta) were synthesized in good yield by Schmidt's glycosylation method. Their subsequent O-debenzylation was proceeded successfully to give the desired products 1-alpha, and 1-beta in good yield, and 2-alpha in a low yield, without 2-beta by only short-timed hydrogenolysis in the presence of palladium-on-carbon (Pd-C) in a CHCl3-MeOH solvent system that included concentrated HCl. Upon enzyme-catalyzed hydrolysis, only 2-alpha was hydrolyzed by the esterase, while both of 1-alpha and 1-beta were not hydrolyzed by any other enzyme such as lipase. These 2-alpha can likely be used as a new water-soluble radical-masked glycosylated spin-label reagent. 相似文献
29.
30.
褐云玛瑙螺(Achatina fulica)胚胎发育不同时间酯酶同工酶分析 总被引:1,自引:0,他引:1
采用聚丙烯酰胺凝胶电泳法,分析了褐云玛瑙螺胚胎发育不同时间的酯酶(EST)同工酶。实验结果表明,在25℃控温条件下胚胎发育早期EST同工酶谱带显示较弱;到初孵幼螺前的整个发育阶段的EST同工酶谱带呈逐渐递增趋势;初孵幼螺EST同工酶谱带增多。两种不同温度(在30℃控温条件下进行了胚胎发育三个不同时间的EST同工酶分析)下胚胎发育至8小时的EST 同工酶谱带差异显著。初孵幼螺前24小时的胚胎发育ES 相似文献