The Experts below are selected from a list of 1677 Experts worldwide ranked by ideXlab platform
Jean Crouzet - One of the best experts on this subject based on the ideXlab platform.
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Transglycosylation reaction of endoxylanase from Trichoderma longibrachiatum
Food Chemistry, 2008Co-Authors: Nadia Kadi, Jean CrouzetAbstract:The study of hydrolytic activities of several enzymatic preparations showed that the Glucanase GL-200 and Xylanase XL-200 enzymatic preparations from Trichoderma longibrachiatum and the Xylanase from Trichoderma viride, possessed an endoxylanase activity useful for the transfer reaction. The enzymatic synthesis of hexylxyloside and hexylxylobioside were achieved by xylose transfer, catalysed by T. longibrachiatum XL-200 xylanase crude preparation, from xylan (donor) to hexanol, with (50%, v:v) or without n-hexane used as co-solvent. Benzyl alcohol was also used as acceptor for the synthesis reaction of benzylxyloside, benzylxylobioside, and benzylxylotrioside, with the T. longibrachiatum XL-200 xylanase crude preparation and partially pure T. longibrachiatum endoxylanase. The transfer reaction due to the T. longibrachiatum endoxylanase was confirmed by the enzymatic synthesis, catalysed by T. longibrachiatum partially pure endoxylanase, of phenyl primeveroside performed from phenyl glucoside and xylan, in the presence of n-hexane. We showed that the T. longibrachiatum endoxylanase was a good tool for the synthesis of xylosyl derivatives (homo- and hetero-xylosides), by transfer reaction.
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Enzymatic synthesis of primeverosides using transfer reaction by Trichoderma longibrachiatum xylanase
Food Chemistry, 2006Co-Authors: Nadia Kadi, Jean CrouzetAbstract:Abstract Enzymatic synthesis of two phenyl xylopyranosyl glucopyranosides, through transfer reaction by Trichoderma longibrachiatum endoxylanase, was achieved in the presence of n -hexane used as solvent, phenyl glucoside (10 mM) as acceptor and xylan (2 g/l) as donor. Kinetic study showed that only one compound, identified by 1 H and 13 C NMR and heteronuclear 2D ( 1 H– 13 C) chemical shift correlation as phenyl primeveroside (phenyl 6- O -β-xylopyranosyl-1-β- d -glucopyranoside), was synthesized when the reaction time was beyond 1 h. Benzyl and hexyl primeverosides were obtained under the same conditions. When several phenyl glucoside concentrations, from 5 to 50 mM, were used with 2 g/l of xylan, a phenyl primeveroside isomer, identified as phenyl 4- O -β-xylopyranosyl-β- d -glucopyranoside, accumulated in the medium whereas the production of phenyl primeveroside decreased. Only phenyl primeveroside was produced when several xylan concentrations from 2 to 10 g/l were used with 10 mM of phenyl glucoside and its concentration in the reaction mixture increased with the increase of xylan concentration.
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enzymatic synthesis of aroma compound xylosides using transfer reaction by Trichoderma longibrachiatum xylanase
Journal of Agricultural and Food Chemistry, 2002Co-Authors: Nadia Kadi, Pascale Chalier, Laurence Belloy, Jean CrouzetAbstract:Enzymatic synthesis of aroma compound xylosides was performed by Trichoderma longibrachiatum xylanase. Information concerning the nature of xylosides present in the reaction medium was obtained by GC-EI-MS, by GC-NCI-MS of TFA derivatives, and by positive FAB-MS of the reaction mixtures. Moreover, the structures of isolated benzyl beta-D-xylopyranoside and 4-O-beta-xylopyranosyl-beta-D-xylopyranoside were established by (1)H and (13)C NMR and heteronuclear two-dimensional ((1)H-(13)C) chemical shift correlation. The results obtained for hexyl and benzyl alcohol xylosides indicated that a reaction implying a transfer of one to two or three xylose units from xylan was involved. The enzyme was able to recognize xylobiose, xylotriose, and xylan as xylose donors. Benzyl xyloside, produced independently of xylobioside and xylotrioside, was found as the major kinetic product of the reaction. Benzyl xyloside was produced in higher quantities and at a higher rate than that obtained for the di- and trixyloside derivatives. The maximum production for benzyl xyloside, 1.29 g/L, was obtained in the presence of hexane (50%) used as cosolvent. Xylosides and xylobiosides of several aroma compounds, (Z)-hex-3-en-1-ol, heptan-2-ol, geraniol, nerol, and citronellol, were synthesized in different amounts, from 850 mg/L for (Z)-hex-3-en-1-yl xylosides to 1.5 mg/L for citronellyl xylosides. No synthesis occurred when menthol, linalool, and eugenol were used as acceptors.
Faten A. Mostafa - One of the best experts on this subject based on the ideXlab platform.
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Improvement of catalytic, thermodynamics and antifungal activity of constitutive Trichoderma longibrachiatum KT693225 exochitinase by covalent coupling to oxidized polysaccharides.
International journal of biological macromolecules, 2018Co-Authors: Walaa A. Abdel Wahab, Abeer A. Abd El Aty, Faten A. MostafaAbstract:Abstract Our study full filled in two main goals preparation of constitutive exochitinase with low cost, utilizing non-chitin containing agricultural wastes, and improving the thermodynamics of purified Trichoderma longibrachiatum KT693225 exochitinase by covalent coupling to sodium periodate activated agar. Central composite design (CCD) was used to improve the chemical modification of Trichoderma longibrachiatum KT693225 exochitinase. Optimum temperature for conjugated exochitinase 60 °C was higher than native form 40 °C. Covalent coupling to oxidized agar caused 4.32, 2.75 and 2.44-fold increase in half-life values at 50, 55 and 60 °C, respectively. Also, conjugated exochitinase showed higher D-values (decimal reduction time) 1790.49 compared to 733.08 min for native form at 60 °C. Moreover, conjugated form had lower deactivation constant rate (kd) 0.39 × 10−3 min−1at 60 °C than native form 1.7 × 10−3 min−1. Native exochitinase exhibited higher activation energy (Ea) 3.39 Kcal·mol−1 and lower energy for denaturation (Ed) 6.88 Kcal·mol−1 compared to 3.21 and 13.05 Kcal·mol−1, respectively for conjugated form. The values of thermodynamic parameters for inactivation of native and conjugated exochitinase indicated that conjugation significantly decreased entropy (ΔS°) and increased enthalpy (ΔH°) and free energy (ΔG°) of deactivation. Conjugated exochitinase exhibited higher antifungal effect against Alternaria alternata, Fusarium oxysporium and Aspergillus niger than native form.
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Thermodynamics characterization and potential textile applications of Trichoderma longibrachiatum KT693225 xylanase
Biocatalysis and Agricultural Biotechnology, 2018Co-Authors: Abeer A. Abd El Aty, Shireen A.a. Saleh, Basma M. Eid, Nabil A. Ibrahim, Faten A. MostafaAbstract:Abstract Our study was a trial to participate in solving two main problems namely, environmental pollution resulting from accumulation and bad disposal of agro-industrial wastes, and high cost of industrial xylanase enzyme production. This was achieved through successful xylanase production by solid-state fermentation of low cost disposable agricultural wastes by marine fungal isolate Trichoderma longibrachiatum KT693225. The highest xylanase production 7.13 ± 0.11 U ml−1 was obtained utilizing rice straw (RS) waste after 7days of fermentation. Xylanase was purified by fractional precipitation with ethanol causing 4.24-fold purification. The 75% ethanol fraction was rich in cellulase, pectinase and α-amylase enzymes beside xylanase. The maximal xylanase activity was obtained at 60 °C, pH 5% and 2.5% xylan concentration. The Km and Vmax were calculated to be 20 mg ml−1 and 20 µmol min−1 ml−1, respectively. The thermostability of T.longibrachiatum KT693225 xylanase was indicated by low Ea (activation energy)and high Ed (energy of denaturation). High T1/2 (half life), D-value (decimal reduction time), ΔH° (enthalpy), ΔG° (free energy) and low Kd (denaturation rate constant), ΔS° (entropy) values at 70 °C emphasized high T.longibrachiatum KT693225 xylanase stability. T.longibrachiatum KT693225 xylanase showed high effectiveness at several textile wet-processing stages including desizing, bioscouring and biofinishing of cellulosic fabrics without adding any additives. These findings in this study have great implications for the future applications of xylanases.
Nadia Kadi - One of the best experts on this subject based on the ideXlab platform.
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Transglycosylation reaction of endoxylanase from Trichoderma longibrachiatum
Food Chemistry, 2008Co-Authors: Nadia Kadi, Jean CrouzetAbstract:The study of hydrolytic activities of several enzymatic preparations showed that the Glucanase GL-200 and Xylanase XL-200 enzymatic preparations from Trichoderma longibrachiatum and the Xylanase from Trichoderma viride, possessed an endoxylanase activity useful for the transfer reaction. The enzymatic synthesis of hexylxyloside and hexylxylobioside were achieved by xylose transfer, catalysed by T. longibrachiatum XL-200 xylanase crude preparation, from xylan (donor) to hexanol, with (50%, v:v) or without n-hexane used as co-solvent. Benzyl alcohol was also used as acceptor for the synthesis reaction of benzylxyloside, benzylxylobioside, and benzylxylotrioside, with the T. longibrachiatum XL-200 xylanase crude preparation and partially pure T. longibrachiatum endoxylanase. The transfer reaction due to the T. longibrachiatum endoxylanase was confirmed by the enzymatic synthesis, catalysed by T. longibrachiatum partially pure endoxylanase, of phenyl primeveroside performed from phenyl glucoside and xylan, in the presence of n-hexane. We showed that the T. longibrachiatum endoxylanase was a good tool for the synthesis of xylosyl derivatives (homo- and hetero-xylosides), by transfer reaction.
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Enzymatic synthesis of primeverosides using transfer reaction by Trichoderma longibrachiatum xylanase
Food Chemistry, 2006Co-Authors: Nadia Kadi, Jean CrouzetAbstract:Abstract Enzymatic synthesis of two phenyl xylopyranosyl glucopyranosides, through transfer reaction by Trichoderma longibrachiatum endoxylanase, was achieved in the presence of n -hexane used as solvent, phenyl glucoside (10 mM) as acceptor and xylan (2 g/l) as donor. Kinetic study showed that only one compound, identified by 1 H and 13 C NMR and heteronuclear 2D ( 1 H– 13 C) chemical shift correlation as phenyl primeveroside (phenyl 6- O -β-xylopyranosyl-1-β- d -glucopyranoside), was synthesized when the reaction time was beyond 1 h. Benzyl and hexyl primeverosides were obtained under the same conditions. When several phenyl glucoside concentrations, from 5 to 50 mM, were used with 2 g/l of xylan, a phenyl primeveroside isomer, identified as phenyl 4- O -β-xylopyranosyl-β- d -glucopyranoside, accumulated in the medium whereas the production of phenyl primeveroside decreased. Only phenyl primeveroside was produced when several xylan concentrations from 2 to 10 g/l were used with 10 mM of phenyl glucoside and its concentration in the reaction mixture increased with the increase of xylan concentration.
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enzymatic synthesis of aroma compound xylosides using transfer reaction by Trichoderma longibrachiatum xylanase
Journal of Agricultural and Food Chemistry, 2002Co-Authors: Nadia Kadi, Pascale Chalier, Laurence Belloy, Jean CrouzetAbstract:Enzymatic synthesis of aroma compound xylosides was performed by Trichoderma longibrachiatum xylanase. Information concerning the nature of xylosides present in the reaction medium was obtained by GC-EI-MS, by GC-NCI-MS of TFA derivatives, and by positive FAB-MS of the reaction mixtures. Moreover, the structures of isolated benzyl beta-D-xylopyranoside and 4-O-beta-xylopyranosyl-beta-D-xylopyranoside were established by (1)H and (13)C NMR and heteronuclear two-dimensional ((1)H-(13)C) chemical shift correlation. The results obtained for hexyl and benzyl alcohol xylosides indicated that a reaction implying a transfer of one to two or three xylose units from xylan was involved. The enzyme was able to recognize xylobiose, xylotriose, and xylan as xylose donors. Benzyl xyloside, produced independently of xylobioside and xylotrioside, was found as the major kinetic product of the reaction. Benzyl xyloside was produced in higher quantities and at a higher rate than that obtained for the di- and trixyloside derivatives. The maximum production for benzyl xyloside, 1.29 g/L, was obtained in the presence of hexane (50%) used as cosolvent. Xylosides and xylobiosides of several aroma compounds, (Z)-hex-3-en-1-ol, heptan-2-ol, geraniol, nerol, and citronellol, were synthesized in different amounts, from 850 mg/L for (Z)-hex-3-en-1-yl xylosides to 1.5 mg/L for citronellyl xylosides. No synthesis occurred when menthol, linalool, and eugenol were used as acceptors.
Abeer A. Abd El Aty - One of the best experts on this subject based on the ideXlab platform.
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Improvement of catalytic, thermodynamics and antifungal activity of constitutive Trichoderma longibrachiatum KT693225 exochitinase by covalent coupling to oxidized polysaccharides.
International journal of biological macromolecules, 2018Co-Authors: Walaa A. Abdel Wahab, Abeer A. Abd El Aty, Faten A. MostafaAbstract:Abstract Our study full filled in two main goals preparation of constitutive exochitinase with low cost, utilizing non-chitin containing agricultural wastes, and improving the thermodynamics of purified Trichoderma longibrachiatum KT693225 exochitinase by covalent coupling to sodium periodate activated agar. Central composite design (CCD) was used to improve the chemical modification of Trichoderma longibrachiatum KT693225 exochitinase. Optimum temperature for conjugated exochitinase 60 °C was higher than native form 40 °C. Covalent coupling to oxidized agar caused 4.32, 2.75 and 2.44-fold increase in half-life values at 50, 55 and 60 °C, respectively. Also, conjugated exochitinase showed higher D-values (decimal reduction time) 1790.49 compared to 733.08 min for native form at 60 °C. Moreover, conjugated form had lower deactivation constant rate (kd) 0.39 × 10−3 min−1at 60 °C than native form 1.7 × 10−3 min−1. Native exochitinase exhibited higher activation energy (Ea) 3.39 Kcal·mol−1 and lower energy for denaturation (Ed) 6.88 Kcal·mol−1 compared to 3.21 and 13.05 Kcal·mol−1, respectively for conjugated form. The values of thermodynamic parameters for inactivation of native and conjugated exochitinase indicated that conjugation significantly decreased entropy (ΔS°) and increased enthalpy (ΔH°) and free energy (ΔG°) of deactivation. Conjugated exochitinase exhibited higher antifungal effect against Alternaria alternata, Fusarium oxysporium and Aspergillus niger than native form.
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Thermodynamics characterization and potential textile applications of Trichoderma longibrachiatum KT693225 xylanase
Biocatalysis and Agricultural Biotechnology, 2018Co-Authors: Abeer A. Abd El Aty, Shireen A.a. Saleh, Basma M. Eid, Nabil A. Ibrahim, Faten A. MostafaAbstract:Abstract Our study was a trial to participate in solving two main problems namely, environmental pollution resulting from accumulation and bad disposal of agro-industrial wastes, and high cost of industrial xylanase enzyme production. This was achieved through successful xylanase production by solid-state fermentation of low cost disposable agricultural wastes by marine fungal isolate Trichoderma longibrachiatum KT693225. The highest xylanase production 7.13 ± 0.11 U ml−1 was obtained utilizing rice straw (RS) waste after 7days of fermentation. Xylanase was purified by fractional precipitation with ethanol causing 4.24-fold purification. The 75% ethanol fraction was rich in cellulase, pectinase and α-amylase enzymes beside xylanase. The maximal xylanase activity was obtained at 60 °C, pH 5% and 2.5% xylan concentration. The Km and Vmax were calculated to be 20 mg ml−1 and 20 µmol min−1 ml−1, respectively. The thermostability of T.longibrachiatum KT693225 xylanase was indicated by low Ea (activation energy)and high Ed (energy of denaturation). High T1/2 (half life), D-value (decimal reduction time), ΔH° (enthalpy), ΔG° (free energy) and low Kd (denaturation rate constant), ΔS° (entropy) values at 70 °C emphasized high T.longibrachiatum KT693225 xylanase stability. T.longibrachiatum KT693225 xylanase showed high effectiveness at several textile wet-processing stages including desizing, bioscouring and biofinishing of cellulosic fabrics without adding any additives. These findings in this study have great implications for the future applications of xylanases.
Quirico Migheli - One of the best experts on this subject based on the ideXlab platform.
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transformants of Trichoderma longibrachiatum overexpressing the β 1 4 endoglucanase gene egl1 show enhanced biocontrol of pythium ultimum on cucumber
Phytopathology, 1998Co-Authors: Quirico Migheli, Laura Dealessi, Andrea Camponogara, Luis Gonzalezcandelas, Daniel RamonvidalAbstract:Migheli, Q., Gonzalez-Candelas, L., Dealessi, L., Camponogara, A., and Ramon-Vidal, D. 1998. Transformants of Trichoderma longibrachiatum overexpressing the β-1,4-endoglucanase gene egl1 show enhanced biocontrol of Pythium ultimum on cucumber. Phytopathology 88:673-677. Nine transformants of Trichoderma longibrachiatum with extra copies of the egl1 gene were studied for mitotic stability, e ndoglucanase production, and biocontrol activity against Pythium ultimum on cucumber seedlings. The transformants showed a significantly higher level of expression of the egl1 gene in comparison to the wild type under both inducing and noninducing growth conditions. Transformants with the egl1 gene under the control of a cons titutive promoter had the highest enzymatic activity. Both the endoglucanase activity and the transforming sequences were stable under nonselective conditions. When applied to cucumber seeds sown in P. ultimum-infested soil, T. longibrachiatum transformants with increased inducible or cons titutive egl1 expression generally were more suppressive than the wild-type strain.
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Transformants of Trichoderma longibrachiatum Overexpressing the β-1,4-Endoglucanase Gene egl1 Show Enhanced Biocontrol of Pythium ultimum on Cucumber
Phytopathology, 1998Co-Authors: Quirico Migheli, Laura Dealessi, Andrea Camponogara, Luis González-candelas, Daniel Ramón-vidalAbstract:ABSTRACT Nine transformants of Trichoderma longibrachiatum with extra copies of the egl1 gene were studied for mitotic stability, endoglucanase production, and biocontrol activity against Pythium ultimum on cucumber seedlings. The transformants showed a significantly higher level of expression of the egl1 gene in comparison to the wild type under both inducing and noninducing growth conditions. Transformants with the egl1 gene under the control of a constitutive promoter had the highest enzymatic activity. Both the endoglucanase activity and the transforming sequences were stable under nonselective conditions. When applied to cucumber seeds sown in P. ultimum-infested soil, T. longibrachiatum transformants with increased inducible or constitutive egl1 expression generally were more suppressive than the wild-type strain.
