The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform

Yuguang Du - One of the best experts on this subject based on the ideXlab platform.

  • cellulosimicrobium cellulans strain e4 5 enzymatic hydrolysis of curdlan for production of 1 3 linked β d glucan oligosaccharides
    Carbohydrate Polymers, 2015
    Co-Authors: Yunbin Fu, Likun Cheng, Yanyu Meng, Yuguang Du, Shuguang Li, Xiaoming Zhao
    Abstract:

    In order to find an efficient enzymatic tool for curdlan degradation to produce (1 -> 3)-linked beta-D-glucan oligosaccharides, strain E4-5 (registration number JN089883, Genbank) was isolated from seaside soil. The 16S rRNA gene sequencing classified it as Cellulosimicrobium cellulans. It was the first reported microorganism that succeeded in degrading high-set heated curdlan blocks. The ferments of strain E4-5 also showed good degradation effects on laminaran and alkali-neutralized curdlan. Due to the products with less amount of glucose, it was assumed that endo-1,3-Beta-Glucanases of strain E4-5 had a greater hydrolyzing effect than exo-1,3-Beta-Glucanases. This indicated that strain E4-5 was a promising microorganism to hydrolyze (1 -> 3)-linked beta-D-glucan. Moreover, alkali-neutralization pretreatment was effective for promoting a more diversified degree of polymerization (DP) of (1 -> 3)-linked beta-D-glucan oligosaccharides under enzymatic hydrolysis and will pave the way for making full use of curdlan for production of glucan oligosaccharides. (C) 2015 Elsevier Ltd. All rights reserved.

Shu-hua Lee - One of the best experts on this subject based on the ideXlab platform.

  • mutational and structural studies of the active site residues in truncated fibrobacter succinogenes 1 3 1 4 β d glucanase
    Acta Crystallographica Section D-biological Crystallography, 2008
    Co-Authors: Li-chu Tsai, Lie-fen Shyur, Hsiaochuan Huang, Chinghua Hsiao, Yuanneng Chiang, Yushiun Lin, Shu-hua Lee
    Abstract:

    1,3-1,4-beta-D-Glucanases (EC 3.2.1.73) specifically hydrolyze beta-1,4-glycosidic bonds located prior to beta-1,3-glycosidic linkages in lichenan or beta-D-glucans. It has been suggested that truncated Fibrobacter succinogenes 1,3-1,4-beta-D-glucanase (TFsBeta-Glucanase) can accommodate five glucose rings in its active site upon enzyme-substrate interaction. In this study, 12 mutant enzymes were created by mutating the conserved residues Gln70, Asn72, Gln81 and Glu85 proposed to bind to substrate subsites +1 and +2 and the catalytic properties of these mutants were determined. The most significant change in catalytic activity was observed on mutation of Gln70, with a 299-fold and 498-fold lower k(cat)/K(m) for the mutants Q70A and Q70I, respectively, compared with the wild-type enzyme. Mutagenesis, kinetic and structural studies revealed that the conserved residues surrounding the active site of TFsBeta-Glucanase at substrate subsites +1 and +2 play an important role in its catalytic function, with the following order of importance: Gln70 > Asn72 > Glu85 > Gln81. The crystal structure of mutant E85I was determined at 2.2 A resolution. Further analysis of the E85I mutant structure revealed that the loop located at the concave site moved approximately 2 A from its position in the native enzyme complex without changing the core structure.

  • Crystal structure of truncated Fibrobacter succinogenes 1,3-1,4-beta-D-glucanase in complex with beta-1,3-1,4-cellotriose.
    Journal of molecular biology, 2005
    Co-Authors: Li-chu Tsai, Lie-fen Shyur, Yi-sheng Cheng, Shu-hua Lee
    Abstract:

    Fibrobacter succinogenes 1,3-1,4-beta-D-glucanase (FsBeta-Glucanase) catalyzes the specific hydrolysis of beta-1,4 glycosidic bonds adjacent to beta-1,3 linkages in beta-D-glucans or lichenan. This is the first report to elucidate the crystal structure of a truncated FsBeta-Glucanase (TFsBeta-Glucanase) in complex with beta-1,3-1,4-cellotriose, a major product of the enzyme reaction. The crystal structures, at a resolution of 2.3 angstroms, reveal that the overall fold of TFsBeta-Glucanase remains virtually unchanged upon sugar binding. The enzyme accommodates five glucose residues, forming a concave active cleft. The beta-1,3-1,4-cellotriose with subsites -3 to -1 bound to the active cleft of TFsBeta-Glucanase with its reducing end subsite -1 close to the key catalytic residues Glu56 and Glu60. All three subsites of the beta-1,3-1,4-cellotriose adopted a relaxed C(1)4 conformation, with a beta-1,3 glycosidic linkage between subsites -2 and -1, and a beta-1,4 glycosidic linkage between subsites -3 and -2. On the basis of the enzyme-product complex structure observed in this study, a catalytic mechanism and substrate binding conformation of the active site of TFsBeta-Glucanase is proposed.

  • crystal structure of a natural circularly permuted jellyroll protein 1 3 1 4 beta d glucanase from fibrobacter succinogenes
    Journal of Molecular Biology, 2003
    Co-Authors: Li-chu Tsai, Lie-fen Shyur, Shu-hua Lee, Sushiang Lin, Hanna S Yuan
    Abstract:

    The 1,3-1,4-beta-D-glucanase from Fibrobacter succinogenes (FsBeta-Glucanase) is classified as one of the family 16 glycosyl hydrolases. It hydrolyzes the glycosidic bond in the mixed-linked glucans containing beta-1,3- and beta-1,4-glycosidic linkages. We constructed a truncated form of recombinant FsBeta-Glucanase containing the catalytic domain from amino acid residues 1-258, which exhibited a higher thermal stability and enzymatic activity than the full-length enzyme. The crystal structure of the truncated FsBeta-Glucanase was solved at a resolution of 1.7A by the multiple wavelength anomalous dispersion (MAD) method using the anomalous signals from the seleno-methionine-labeled protein. The overall topology of the truncated FsBeta-Glucanase consists mainly of two eight-stranded anti-parallel beta-sheets arranged in a jellyroll beta-sandwich, similar to the fold of many glycosyl hydrolases and carbohydrate-binding modules. Sequence comparison with other bacterial glucanases showed that FsBeta-Glucanase is the only naturally occurring circularly permuted Beta-Glucanase with reversed sequences. Structural comparison shows that the engineered circular-permuted Bacillus enzymes are more similar to their parent enzymes with which they share approximately 70% sequence identity, than to the naturally occurring FsBeta-Glucanase of similar topology with 30% identity. This result suggests that protein structure relies more on sequence identity than topology. The high-resolution structure of FsBeta-Glucanase provides a structural rationale for the different activities obtained from a series of mutant glucanases and a basis for the development of engineered enzymes with increased activity and structural stability.

Yunbin Fu - One of the best experts on this subject based on the ideXlab platform.

  • cellulosimicrobium cellulans strain e4 5 enzymatic hydrolysis of curdlan for production of 1 3 linked β d glucan oligosaccharides
    Carbohydrate Polymers, 2015
    Co-Authors: Yunbin Fu, Likun Cheng, Yanyu Meng, Yuguang Du, Shuguang Li, Xiaoming Zhao
    Abstract:

    In order to find an efficient enzymatic tool for curdlan degradation to produce (1 -> 3)-linked beta-D-glucan oligosaccharides, strain E4-5 (registration number JN089883, Genbank) was isolated from seaside soil. The 16S rRNA gene sequencing classified it as Cellulosimicrobium cellulans. It was the first reported microorganism that succeeded in degrading high-set heated curdlan blocks. The ferments of strain E4-5 also showed good degradation effects on laminaran and alkali-neutralized curdlan. Due to the products with less amount of glucose, it was assumed that endo-1,3-Beta-Glucanases of strain E4-5 had a greater hydrolyzing effect than exo-1,3-Beta-Glucanases. This indicated that strain E4-5 was a promising microorganism to hydrolyze (1 -> 3)-linked beta-D-glucan. Moreover, alkali-neutralization pretreatment was effective for promoting a more diversified degree of polymerization (DP) of (1 -> 3)-linked beta-D-glucan oligosaccharides under enzymatic hydrolysis and will pave the way for making full use of curdlan for production of glucan oligosaccharides. (C) 2015 Elsevier Ltd. All rights reserved.

Li-chu Tsai - One of the best experts on this subject based on the ideXlab platform.

  • mutational and structural studies of the active site residues in truncated fibrobacter succinogenes 1 3 1 4 β d glucanase
    Acta Crystallographica Section D-biological Crystallography, 2008
    Co-Authors: Li-chu Tsai, Lie-fen Shyur, Hsiaochuan Huang, Chinghua Hsiao, Yuanneng Chiang, Yushiun Lin, Shu-hua Lee
    Abstract:

    1,3-1,4-beta-D-Glucanases (EC 3.2.1.73) specifically hydrolyze beta-1,4-glycosidic bonds located prior to beta-1,3-glycosidic linkages in lichenan or beta-D-glucans. It has been suggested that truncated Fibrobacter succinogenes 1,3-1,4-beta-D-glucanase (TFsBeta-Glucanase) can accommodate five glucose rings in its active site upon enzyme-substrate interaction. In this study, 12 mutant enzymes were created by mutating the conserved residues Gln70, Asn72, Gln81 and Glu85 proposed to bind to substrate subsites +1 and +2 and the catalytic properties of these mutants were determined. The most significant change in catalytic activity was observed on mutation of Gln70, with a 299-fold and 498-fold lower k(cat)/K(m) for the mutants Q70A and Q70I, respectively, compared with the wild-type enzyme. Mutagenesis, kinetic and structural studies revealed that the conserved residues surrounding the active site of TFsBeta-Glucanase at substrate subsites +1 and +2 play an important role in its catalytic function, with the following order of importance: Gln70 > Asn72 > Glu85 > Gln81. The crystal structure of mutant E85I was determined at 2.2 A resolution. Further analysis of the E85I mutant structure revealed that the loop located at the concave site moved approximately 2 A from its position in the native enzyme complex without changing the core structure.

  • Crystal structure of truncated Fibrobacter succinogenes 1,3-1,4-beta-D-glucanase in complex with beta-1,3-1,4-cellotriose.
    Journal of molecular biology, 2005
    Co-Authors: Li-chu Tsai, Lie-fen Shyur, Yi-sheng Cheng, Shu-hua Lee
    Abstract:

    Fibrobacter succinogenes 1,3-1,4-beta-D-glucanase (FsBeta-Glucanase) catalyzes the specific hydrolysis of beta-1,4 glycosidic bonds adjacent to beta-1,3 linkages in beta-D-glucans or lichenan. This is the first report to elucidate the crystal structure of a truncated FsBeta-Glucanase (TFsBeta-Glucanase) in complex with beta-1,3-1,4-cellotriose, a major product of the enzyme reaction. The crystal structures, at a resolution of 2.3 angstroms, reveal that the overall fold of TFsBeta-Glucanase remains virtually unchanged upon sugar binding. The enzyme accommodates five glucose residues, forming a concave active cleft. The beta-1,3-1,4-cellotriose with subsites -3 to -1 bound to the active cleft of TFsBeta-Glucanase with its reducing end subsite -1 close to the key catalytic residues Glu56 and Glu60. All three subsites of the beta-1,3-1,4-cellotriose adopted a relaxed C(1)4 conformation, with a beta-1,3 glycosidic linkage between subsites -2 and -1, and a beta-1,4 glycosidic linkage between subsites -3 and -2. On the basis of the enzyme-product complex structure observed in this study, a catalytic mechanism and substrate binding conformation of the active site of TFsBeta-Glucanase is proposed.

  • crystal structure of a natural circularly permuted jellyroll protein 1 3 1 4 beta d glucanase from fibrobacter succinogenes
    Journal of Molecular Biology, 2003
    Co-Authors: Li-chu Tsai, Lie-fen Shyur, Shu-hua Lee, Sushiang Lin, Hanna S Yuan
    Abstract:

    The 1,3-1,4-beta-D-glucanase from Fibrobacter succinogenes (FsBeta-Glucanase) is classified as one of the family 16 glycosyl hydrolases. It hydrolyzes the glycosidic bond in the mixed-linked glucans containing beta-1,3- and beta-1,4-glycosidic linkages. We constructed a truncated form of recombinant FsBeta-Glucanase containing the catalytic domain from amino acid residues 1-258, which exhibited a higher thermal stability and enzymatic activity than the full-length enzyme. The crystal structure of the truncated FsBeta-Glucanase was solved at a resolution of 1.7A by the multiple wavelength anomalous dispersion (MAD) method using the anomalous signals from the seleno-methionine-labeled protein. The overall topology of the truncated FsBeta-Glucanase consists mainly of two eight-stranded anti-parallel beta-sheets arranged in a jellyroll beta-sandwich, similar to the fold of many glycosyl hydrolases and carbohydrate-binding modules. Sequence comparison with other bacterial glucanases showed that FsBeta-Glucanase is the only naturally occurring circularly permuted Beta-Glucanase with reversed sequences. Structural comparison shows that the engineered circular-permuted Bacillus enzymes are more similar to their parent enzymes with which they share approximately 70% sequence identity, than to the naturally occurring FsBeta-Glucanase of similar topology with 30% identity. This result suggests that protein structure relies more on sequence identity than topology. The high-resolution structure of FsBeta-Glucanase provides a structural rationale for the different activities obtained from a series of mutant glucanases and a basis for the development of engineered enzymes with increased activity and structural stability.

Yanyu Meng - One of the best experts on this subject based on the ideXlab platform.

  • cellulosimicrobium cellulans strain e4 5 enzymatic hydrolysis of curdlan for production of 1 3 linked β d glucan oligosaccharides
    Carbohydrate Polymers, 2015
    Co-Authors: Yunbin Fu, Likun Cheng, Yanyu Meng, Yuguang Du, Shuguang Li, Xiaoming Zhao
    Abstract:

    In order to find an efficient enzymatic tool for curdlan degradation to produce (1 -> 3)-linked beta-D-glucan oligosaccharides, strain E4-5 (registration number JN089883, Genbank) was isolated from seaside soil. The 16S rRNA gene sequencing classified it as Cellulosimicrobium cellulans. It was the first reported microorganism that succeeded in degrading high-set heated curdlan blocks. The ferments of strain E4-5 also showed good degradation effects on laminaran and alkali-neutralized curdlan. Due to the products with less amount of glucose, it was assumed that endo-1,3-Beta-Glucanases of strain E4-5 had a greater hydrolyzing effect than exo-1,3-Beta-Glucanases. This indicated that strain E4-5 was a promising microorganism to hydrolyze (1 -> 3)-linked beta-D-glucan. Moreover, alkali-neutralization pretreatment was effective for promoting a more diversified degree of polymerization (DP) of (1 -> 3)-linked beta-D-glucan oligosaccharides under enzymatic hydrolysis and will pave the way for making full use of curdlan for production of glucan oligosaccharides. (C) 2015 Elsevier Ltd. All rights reserved.