Journal of Molecular Catalysis B-enzymatic最新文献_第8页

Two- way dynamics in β-glucosidase catalysis β-葡萄糖苷酶催化的双向动力学

Journal of Molecular Catalysis B-enzymatic Pub Date : 2016-11-01 Epub Date: 2016-08-17 DOI: 10.1016/j.molcatb.2016.08.010

Sneha Sawant , Sachinkumar Birhade , Annamma Anil , Harry Gilbert , Arvind Lali

{"title":"Two- way dynamics in β-glucosidase catalysis","authors":"Sneha Sawant , Sachinkumar Birhade , Annamma Anil , Harry Gilbert , Arvind Lali","doi":"10.1016/j.molcatb.2016.08.010","DOIUrl":"10.1016/j.molcatb.2016.08.010","url":null,"abstract":"<div><p>Product inhibition of β-glucosidase is considered as one of the central rate limiting steps as it starts accumulation of intermediates responsible for the slowdown of the cellulose hydrolysis. Feedback inhibitions exhibited by glucose and other oligosaccharides on the cellulose hydrolyzing enzyme reduces the rate of hydrolysis bringing the entire process to standstill. However, the exact mechanism of this catalytic slowdown is still elusive. In present study, β-glucosidases were investigated for their activities under high glucose and cellobiose concentrations. β-glucosidases recognizes cellobiose a true substrate and hydrolyzes it resulting in glucose or transglycosylates it to give cellotriose. Our observation highlight that rates of reaction for cellotriose synthesis and glucose formation are mainly concentration driven and are dynamically adjusted based on cellobiose concentration in the reaction system. We therefore conclude that critical concentration of DP2: DP3 influences hydrolysis or transglycosylation and any modulation to this ratio influences the dynamics of β-glucosidases hydrolysis.</p></div>","PeriodicalId":16416,"journal":{"name":"Journal of Molecular Catalysis B-enzymatic","volume":"133 ","pages":"Pages 161-166"},"PeriodicalIF":0.0,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.molcatb.2016.08.010","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88802048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 11

Removal of lactose in crude galacto-oligosaccharides by β-galactosidase from Kluyveromyces lactis 利用克鲁维菌β-半乳糖苷酶去除粗半乳糖低聚糖中的乳糖

Journal of Molecular Catalysis B-enzymatic Pub Date : 2016-11-01 Epub Date: 2016-07-25 DOI: 10.1016/j.molcatb.2016.07.014

Luciana Santibáñez , Lucía Fernández-Arrojo , Cecilia Guerrero , Francisco J. Plou , Andrés Illanes

{"title":"Removal of lactose in crude galacto-oligosaccharides by β-galactosidase from Kluyveromyces lactis","authors":"Luciana Santibáñez , Lucía Fernández-Arrojo , Cecilia Guerrero , Francisco J. Plou , Andrés Illanes","doi":"10.1016/j.molcatb.2016.07.014","DOIUrl":"https://doi.org/10.1016/j.molcatb.2016.07.014","url":null,"abstract":"<div><p>In order to remove the residual lactose in crude galacto-oligosaccharides (GOS), different commercial soluble β-galactosidases from <em>Kluyveromyces lactis</em> (Lactozym Pure 6500L, Maxilact L2000, Lactase NL and Biolactasa-NL) and reaction conditions (temperature, total carbohydrate concentration and enzyme:substrate mass ratio) were evaluated. To select the best biocatalyst, the hydrolytic activity on <em>o</em>-NPG and thermal stability of all enzymes were evaluated in the absence and presence of three cations (Co<sup>2+</sup>, Mg<sup>2+</sup>, Mn<sup>2+</sup>) at different concentrations. The enzyme source, cation and cation concentration were selected to obtain the highest hydrolytic activity and thermal stability. Then lactose hydrolysis of raw GOS was assessed varying the temperature (30°C–45°C), total carbohydrate concentration (10%-50%) and enzyme:substrate mass ratio (50IUg<sup>−1</sup>–400IUg<sup>−1</sup>) and considering the lactose percentage decrease as response parameter (D<sub>L</sub>). Lactase NL was selected as the best enzyme, with a hydrolytic activity of 286IUmg<sup>−1</sup> and a half-life of 9h at 35°C in the presence of 1mM Mn<sup>2+</sup>. The best reaction conditions for lactose hydrolysis employing the selected enzyme were 35°C, 50% initial carbohydrate concentration and 135IUg<sup>−1</sup>. At such conditions of lactose hydrolysis, 70% reduction of lactose in raw GOS was obtained, with an increase of 48% in monosaccharides and of 30% in GOS. This pre-hydrolytic step is a key aspect for the subsequent purification of GOS by nanofiltration or selected bioconversion, in which monosaccharides can be removed efficiently producing GOS of high purity.</p></div>","PeriodicalId":16416,"journal":{"name":"Journal of Molecular Catalysis B-enzymatic","volume":"133 ","pages":"Pages 85-91"},"PeriodicalIF":0.0,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.molcatb.2016.07.014","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"137190004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

An unexpected inversion of CAL-B enantiopreference based on substrate engineering of 2-bromoesters: Effect of (R)-1-phenylethyl moiety 基于2-溴酯底物工程的CAL-B对映性的意外反转:(R)-1-苯乙基部分的影响

Journal of Molecular Catalysis B-enzymatic Pub Date : 2016-11-01 Epub Date: 2017-02-02 DOI: 10.1016/j.molcatb.2017.02.001

Thiago Sabino da Silva, Suelem Kluconski Campos, Alfredo R.M. de Oliveira, Leandro Piovan

{"title":"An unexpected inversion of CAL-B enantiopreference based on substrate engineering of 2-bromoesters: Effect of (R)-1-phenylethyl moiety","authors":"Thiago Sabino da Silva, Suelem Kluconski Campos, Alfredo R.M. de Oliveira, Leandro Piovan","doi":"10.1016/j.molcatb.2017.02.001","DOIUrl":"10.1016/j.molcatb.2017.02.001","url":null,"abstract":"<div><p><em>Candida antarctica</em> lipase B (CAL-B) is one of the most useful enzymes for preparation of optically active alcohols and amines. However, CAL-B substrate’s scope for enzymatic kinetic resolution (EKR) of carboxylic acids and their derivatives is limited, especially by low stereoselectivity. In an attempt to overcome this drawback, we decided to employ substrate engineering of enzymatic transesterification of 2-bromobutyric esters by changing the alcohol moiety of the structure. The modifications in the substrate resulted mainly in alterations of the conversion rate, but the inclusion of a chiral alcohol moiety such as (<em>R</em>)-1-phenylethanol resulted in inversion of CAL-B enantiopreference. When esters containing ordinary achiral aliphatic alcohol moiety were used, CAL-B presented <em>S</em>-selectivity. This selectivity was unexpectedly changed to <em>R</em> when an ester containing (<em>R</em>)-1-phenylethyl alcohol moiety was introduced. The use of (<em>R</em>)-1-phenylethanol and its derivatives as nucleophiles in the EKR of the 2-bromobutyric esters also resulted in the inversion of enzymatic enantiopreference. This is the first time that CAL-B acyl enantiopreference has been switched by the chiral nature of the alcohol moiety.</p></div>","PeriodicalId":16416,"journal":{"name":"Journal of Molecular Catalysis B-enzymatic","volume":"133 ","pages":"Pages S317-S323"},"PeriodicalIF":0.0,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.molcatb.2017.02.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76854063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Cyclodextrin glycosyltransferase variants experience different modes of product inhibition 环糊精糖基转移酶变体经历不同的产物抑制模式

Journal of Molecular Catalysis B-enzymatic Pub Date : 2016-11-01 Epub Date: 2016-08-24 DOI: 10.1016/j.molcatb.2016.08.016

Caiming Li , Qi Xu , Zhengbiao Gu , Shuangdi Chen , Jing Wu , Yan Hong , Li Cheng , Zhaofeng Li

引用次数: 7

Improved enantioselective esterification of dl-menthol catalyzed by immobilized TL 100L lipase 固定化tl100l脂肪酶催化dl-薄荷醇的对映选择性酯化反应

Journal of Molecular Catalysis B-enzymatic Pub Date : 2016-11-01 Epub Date: 2017-01-29 DOI: 10.1016/j.molcatb.2017.01.013

Jie Sun, Chao Ding, Jian-Yong Zheng, Xin-Jun Yu, Man Zhao, Zhao Wang

{"title":"Improved enantioselective esterification of dl-menthol catalyzed by immobilized TL 100L lipase","authors":"Jie Sun, Chao Ding, Jian-Yong Zheng, Xin-Jun Yu, Man Zhao, Zhao Wang","doi":"10.1016/j.molcatb.2017.01.013","DOIUrl":"10.1016/j.molcatb.2017.01.013","url":null,"abstract":"<div><p>Lipozyme TL IM exhibits high enantioselectivity for the resolution of <span>dl</span>-menthol by the esterification of <span>l</span>-menthol. However, in this study, some factors such as protein loss, enzyme inactivation, and acetaldehyde damage greatly reduced the reaction conversion. For relieving the effects of these factors, macroporous resin that absorbs more protein was selected to immobilize Lipozyme TL 100L lipase with trehalose as the modifying agent. The immobilized lipases retained 37.2% of their initial activity after 8 times of repeated use. A packed-bed reaction system was designed to prevent the leaching of adsorbed lipase molecules out of the macroporous resin pore and to outflow acetaldehyde with the product. The immobilized lipase was continuously used with ee<sub>p</sub>   <!-->g/L/h. This process is readily applicable to large-scale preparation for optically active menthol.</p></div>","PeriodicalId":16416,"journal":{"name":"Journal of Molecular Catalysis B-enzymatic","volume":"133 ","pages":"Pages S271-S276"},"PeriodicalIF":0.0,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.molcatb.2017.01.013","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80443869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Immobilization of Y. lipolytica lipase and the continuous synthesis of geranyl propionate 脂肪酶的固定化及丙酸香叶醇的连续合成

Journal of Molecular Catalysis B-enzymatic Pub Date : 2016-11-01 Epub Date: 2017-01-29 DOI: 10.1016/j.molcatb.2017.01.019

Jing Tang , Gang Chen , Lu Wang , Ming Miao , Bo Jiang , Biao Feng

{"title":"Immobilization of Y. lipolytica lipase and the continuous synthesis of geranyl propionate","authors":"Jing Tang , Gang Chen , Lu Wang , Ming Miao , Bo Jiang , Biao Feng","doi":"10.1016/j.molcatb.2017.01.019","DOIUrl":"10.1016/j.molcatb.2017.01.019","url":null,"abstract":"<div><p>In this study, <em>Y. lipolytica</em> lipase LIP2 (Lip2) was immobilized on the macroporous adsorptive resin DA201-C in <em>n</em>-heptane and then used to catalyze the continuous synthesis of geranyl propionate in a continuous stirred tank reactor (CSTR). With the lipase loading of 0.01g/g resin, 25°C and adsorption for 3h, the immobilization efficiency can be up to 98.6% and the synthetic activity of the lipase was 690.8U/g after immobilization, representing an increase of 28.5% compared with the free lipase (synthetic activity 537.2U/g). The immobilized Lip2 was used to generate geranyl propionate in CSTR, the continuous production of geranyl propionate was performed with 3g of immobilized Lip2 at 35°C. At the flow rate of 6mL/h the process can maintain its steady state at least for 12h, which was about three times of the average residence time, and the esterification ratio of 72.8% could be attained. Finally, FT-IR and NMR were used to identify the ester.</p></div>","PeriodicalId":16416,"journal":{"name":"Journal of Molecular Catalysis B-enzymatic","volume":"133 ","pages":"Pages S311-S316"},"PeriodicalIF":0.0,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.molcatb.2017.01.019","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77360510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Aspergillus flavipes methionine γ-lyase-dextran conjugates with enhanced structural, proteolytic stability and anticancer efficiency 黄曲霉甲硫氨酸γ-裂解酶-葡聚糖缀合物具有增强的结构、蛋白水解稳定性和抗癌效率

Journal of Molecular Catalysis B-enzymatic Pub Date : 2016-11-01 DOI: 10.1016/J.MOLCATB.2016.11.002

A. El-Sayed, Abdalla E A Hassan, A. Shindia, Shaimaa G. A. Mohamed, M. Sitohy

引用次数: 28

Multi-response behavior of aminosulfonaphthole system 氨基磺唑体系的多响应行为

Journal of Molecular Catalysis B-enzymatic Pub Date : 2016-11-01 Epub Date: 2016-09-03 DOI: 10.1016/j.molcatb.2016.09.002

Fatih Doğan , İsmet Kaya , Kevser Temizkan

{"title":"Multi-response behavior of aminosulfonaphthole system","authors":"Fatih Doğan , İsmet Kaya , Kevser Temizkan","doi":"10.1016/j.molcatb.2016.09.002","DOIUrl":"10.1016/j.molcatb.2016.09.002","url":null,"abstract":"<div><p><span>Here, we report regioselectively functionalized synthesis, as well as photo physical, electrochemical, and thermal, of a novel water-soluble conjugated polymer. For this purpose, horseradish peroxidase (HRP)-catalyzed polymerization of a multifunctional monomer, 7-amino-4-hydroxy-2-naphthalene sulfonic acid (AHNAPSA) was carried out by using hydrogen peroxide as the oxidant at room temperature for 24</span> <!-->h under air. The structure of poly(7-amino-4-hydroxy-2-naphthalene sulfonic acid), (PAHNAPSA) was identified by using nuclear magnetic resonance, infrared and ultraviolet-visible. Further characterization was performed by means of gel permeation chromatography (GPC), thermogravimetry (TG), differential scanning calorimetry (DSC), cyclic voltammetry (CV), photoluminescence (PL), dynamic light scattering (DLS) and solid state conductivity measurements. The spectral analysis results exhibited functional group selective polymerization of the monomer containing a multi-active center. Solvent effects on the optical, electrochemical and photo physical properties of PAHNAPSA were investigated by using five different solvents. PAHNAPSA presented an irreversible redox characterization at different scan rates. Optical band gap of PAHNAPSA is also found in the range of 3.18 eV to 3.55 eV. The fluorescence measurements were utilized to investigate the photochemical behaviors of PAHNAPSA in selected polar solvents. Accordingly, PAHNAPSA surprisingly presented multicolor emission behavior with relatively high quantum yield in all selected solvents. In addition, PAHNAPSA presented a reversible pH-responsive behavior and also had high selectivity and sensitivity towards chromium ions. Finally, the kinetic parameters associated with the solid state thermal degradation of PAHNAPSA were calculated from isoconversional methods. The TG/DTG analysis showed that PAHNAPSA followed a diffusion controlled degradation mechanism in N<sub>2</sub>.</p></div>","PeriodicalId":16416,"journal":{"name":"Journal of Molecular Catalysis B-enzymatic","volume":"133 ","pages":"Pages 234-245"},"PeriodicalIF":0.0,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.molcatb.2016.09.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89453329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 7

Double mutations enhance β-cyclization activity of cyclodextrin glycosyltransferase from Bacillus circulans 双突变增强环状芽孢杆菌环糊精糖基转移酶β-环化活性

Journal of Molecular Catalysis B-enzymatic Pub Date : 2016-11-01 Epub Date: 2016-12-14 DOI: 10.1016/j.molcatb.2016.12.002

Min Huang , Junyan Ren , Caiming Li , Zhengbiao Gu , Yan Hong , Li Cheng , Zhaofeng Li

{"title":"Double mutations enhance β-cyclization activity of cyclodextrin glycosyltransferase from Bacillus circulans","authors":"Min Huang , Junyan Ren , Caiming Li , Zhengbiao Gu , Yan Hong , Li Cheng , Zhaofeng Li","doi":"10.1016/j.molcatb.2016.12.002","DOIUrl":"10.1016/j.molcatb.2016.12.002","url":null,"abstract":"<div><p>A major drawback to the industrial production of β-cyclodextrin is the limited β-cyclization activity of cyclodextrin glycosyltransferase (CGTase). Here, we construct mutants of the β-CGTase from <em>Bacillus circulans</em> strain STB01 that contain single substitutions at Tyr89 and double substitutions at Tyr89 and Asp577. The results show that the double mutants Y89G/D577R, Y89D/D577R, and Y89N/D577R display enhanced β-cyclization activity, and have higher β-cyclization activity than that of the three single Tyr89 mutants. The double mutant Y89D/D577R exhibited the highest β-cyclization activity and β-cyclodextrin production, increasing 35.1% and 12.4% compared with those of the wild-type CGTase, respectively. The β-cyclization activity of double mutant Y89D/D577R is also higher than that of the single mutant D577R, which had the highest β-cyclization activity among the mutants prepared in our previous studies. The enhanced β-cyclization activity of these mutants may be a result of intermolecular interactions that stabilize intermediates in the β-cyclization reaction. Thus, double mutant Y89D/D577R is much more suitable for industrial β-cyclodextrin production than the wild-type enzyme.</p></div>","PeriodicalId":16416,"journal":{"name":"Journal of Molecular Catalysis B-enzymatic","volume":"133 ","pages":"Pages S100-S105"},"PeriodicalIF":0.0,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.molcatb.2016.12.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81739528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

The Candida rugosa lipase adsorbed onto titania as nano biocatalyst with improved thermostability and reuse potential in aqueous and organic media 念珠菌脂肪酶作为纳米生物催化剂吸附在二氧化钛上，在水和有机介质中具有更好的热稳定性和重用潜力

Journal of Molecular Catalysis B-enzymatic Pub Date : 2016-11-01 Epub Date: 2017-06-23 DOI: 10.1016/j.molcatb.2017.06.001

Lidija T. Izrael Živković , Ljiljana S. Živković , Vladimir P. Beškoski , Kristina R. Gopčević , Bojan M. Jokić , Dragoslav S. Radosavljević , Ivanka M. Karadžić

{"title":"The Candida rugosa lipase adsorbed onto titania as nano biocatalyst with improved thermostability and reuse potential in aqueous and organic media","authors":"Lidija T. Izrael Živković , Ljiljana S. Živković , Vladimir P. Beškoski , Kristina R. Gopčević , Bojan M. Jokić , Dragoslav S. Radosavljević , Ivanka M. Karadžić","doi":"10.1016/j.molcatb.2017.06.001","DOIUrl":"10.1016/j.molcatb.2017.06.001","url":null,"abstract":"<div><p>The immobilization of <em>Candida rugosa</em> lipase by adsorption was performed onto commercial titania powder (Degussa P25). The change of titania particles surface was diagnosed by means of FTIR and FESEM analysis, as well as by shift of zeta potential value towards that of lipase. A detailed study of the effect of immobilization on enzyme kinetic, temperature stability, as well as on potential for its reuse in aqueous organic media was undertaken. Immobilization of lipase altered enzyme affinity toward substrates with different length of carbon chain in hydrolytic reaction. The Vmax value decreased 2–8-fold, where major constraint was registered for the ester containing the longest carbon chain. Thermostability of lipase improved more than 7-fold at 60°C. Significant potential for reuse in water solutions was also found after immobilization. In cyclohexane immobilized lipase catalyzed synthesis of amyl octanoate by ping-pong bi–bi mechanism with inhibition by amyl alcohol. Obtained kinetic constants were Vmax=26.4μmolmin<sup>−1</sup>,K<sub>Ac</sub>    =0.2mol/L and K<sub>i,Al</sub>   <!-->mol/L. Esterification activity remained 60% after 5 reuse cycles in cyclohexane indicating moderate reuse stability.</p></div>","PeriodicalId":16416,"journal":{"name":"Journal of Molecular Catalysis B-enzymatic","volume":"133 ","pages":"Pages S533-S542"},"PeriodicalIF":0.0,"publicationDate":"2016-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.molcatb.2017.06.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86429458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6