The Experts below are selected from a list of 192 Experts worldwide ranked by ideXlab platform
Fei Tao - One of the best experts on this subject based on the ideXlab platform.
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Chemoenzymatic Synthesis of N-Acetyl-d-Neuraminic Acid from N-Acetyl-d-Glucosamine by Using the Spore Surface-Displayed N-Acetyl-d-Neuraminic Acid Aldolase
Applied and environmental microbiology, 2011Co-Authors: Chao Gao, Xifeng Zhang, Bin Che, Jianhua Qiu, Fei TaoAbstract:ABSTRACT Chemoenzymatic synthesis of N-acetyl-d-Neuraminic Acid from N-acetyl-d-glucosamine using the spore surface-displayed N-acetyl-d-Neuraminic Acid aldolase at a high concentration (53.9 g liter−1) was achieved in this study. Thus, displaying a target enzyme on the surface of spores might be an alternative for integration of biocatalytic conversion into chemical synthesis.
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Production of N-Acetyl-d-Neuraminic Acid by Use of an Efficient Spore Surface Display System
Applied and environmental microbiology, 2011Co-Authors: Chao Gao, Xifeng Zhang, Bin Che, Jianhua Qiu, Fei TaoAbstract:Production of N-acetyl-D-Neuraminic Acid (Neu5Ac) via biocatalysis is traditionally conducted using isolated enzymes or whole cells. The use of isolated enzymes is restricted by the time-consuming purification process, whereas the application of whole cells is limited by the permeability barrier presented by the microbial cell membrane. In this study, a novel type of biocatalyst, Neu5Ac aldolase presented on the surface of Bacillus subtilis spores, was used for the production of Neu5Ac. Under optimal conditions, Neu5Ac at a high concentration (54.7 g liter⁻¹) and a high yield (90.2%) was obtained under a 5-fold excess of pyruvate over N-acetyl-D-mannosamine. The novel biocatalyst system, which is able to express and immobilize the target enzyme simultaneously on the surface of B. subtilis spores, represents a suitable alternative for value-added chemical production.
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Biotechnological production and applications of N -acetyl- d -Neuraminic Acid: current state and perspectives
Applied microbiology and biotechnology, 2010Co-Authors: Fei Tao, Yinan ZhangAbstract:N-Acetyl-D-Neuraminic Acid (Neu5Ac) and its derivates are a very important group of biomolecules because these sugars occupy the terminal positions in numerous macromolecules, such as the glycans of glycoproteins, and are involved in many biological and pathological phenomena. The synthesis and applications of Neu5Ac are attracting much interest due to the potential applications of this compound in the pharmaceutical industry, such as in the synthesis of the anti-flu drug zanamivir. In this review article, we discuss existing knowledge on the biotechnological production and applications of Neu5Ac and also propose some guidelines for future studies.
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An efficient method for N-acetyl-D-Neuraminic Acid production using coupled bacterial cells with a safe temperature-induced system.
Applied microbiology and biotechnology, 2009Co-Authors: Yinan Zhang, Fei Tao, Jianhua QiuAbstract:N-Acetyl-d-Neuraminic Acid (Neu5Ac) is a precursor for producing many pharmaceutical drugs such as zanamivir which have been used in clinical trials to treat and prevent the infection with influenza virus, such as the avian influenza virus H5N1 and the current 2009 H1N1. Two recombinant Escherichia coli strains capable of expressing N-acetyl-d-glucosamine 2-epimerase and N-acetyl-d-Neuraminic Acid aldolase were constructed based on a highly efficient temperature-responsive expression system which is safe compared to chemical-induced systems and coupled in Neu5Ac production. Carbon sources were optimized for Neu5Ac production, and the concentration effects of carbon sources on the production were investigated. With 2,200 mM pyruvate as carbon source and substrate, 61.9 mM (19.1 g l−1) Neu5Ac was produced from 200 mM N-acetyl-d-glucosamine (GlcNAc) in 36 h by the coupled cells. Our Neu5Ac biosynthetic process is favorable compared with natural product extraction, chemical synthesis, or even many other biocatalysis processes.
Robert J. Linhardt - One of the best experts on this subject based on the ideXlab platform.
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Stereoselective synthesis of a C-linked Neuraminic Acid disaccharide: potential building block for the synthesis of C-analogues of polysialic Acids.
The Journal of organic chemistry, 2008Co-Authors: Jin-hwan Kim, Fei Huang, Robert J. LinhardtAbstract:C-Linked Neuraminic Acid disaccharide was synthesized in a diastereoselective manner from a sulfone donor and aldehyde acceptor, which was protected as a propargyl ether, through a samarium-mediated coupling reaction. The resulting disaccharide has acetal and phenyl sulfide functional groups that can be easily converted into aldehyde and phenyl sulfone groups by photolysis and oxidation reactions to serve as disaccharide acceptor and donor, respectively.
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Chemoenzymatic synthesis of Neuraminic Acid containing C-glycoside polymers.
Organic letters, 2003Co-Authors: Qun Wang, Jonathan S. Dordick, Robert J. LinhardtAbstract:Two Neuraminic Acid-based, C-glycoside polymers were synthesized. Preliminary studies on one of these polymers showed potent neuraminidase inhibitory activity, suggesting potential utility as an antipathogenic surface coating for the preparation of antimicrobial biomaterials.
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Synthesis of a serine-based Neuraminic Acid C-glycoside.
The Journal of organic chemistry, 2003Co-Authors: Qun Wang, Robert J. LinhardtAbstract:Cell-surface carbohydrates are classified by the nature of their linkages to the protein as either N-linked or O-linked. O- and N-glycans are involved in a number of important biological functions. These activities can be lost on glycoprotein catabolism when these glycan linkages are enzymatically hydrolyzed. The design and synthesis of novel C-linked glycans should provide catabolically stable glycoproteins useful for understanding and regulating important biological processes. Our efforts are currently directed toward the synthesis of C-glycosides of ulosonic Acids. This paper describes the first synthesis of a serine-based Neuraminic Acid C-glycoside. The protecting group chemistry required for both carbohydrate and peptide syntheses complicates this approach. Different protecting group strategies were investigated for use in the samarium diiodide mediated C-glycosylation reaction. The key elements of our synthetic approach involve the following: (i) the substitution of homoserine for serine in the C-glycosylation reaction to introduce a carbon in place of the O-glycosidic oxygen, (ii) the use of benzyloxycarbonyl as a homoserine protecting group, compatible with samarium diiodide mediated C-glycosylation reaction, and (iii) the reduction of the carbonyl group in homoserine early in the synthesis to improve C-glycosylation yield and to avoid lactone formation. Using this combined approach, we prepared 4-O-acetyl-4-[2-C-(1-methyl 5-acetamido 4,7,8,9-tetra-O-acetyl-2,6-anhydro-3,5-dideoxy-d-erythro-l-manno-nononate)]-2S-(benzyloxycarbonyl)amino-1-carboxylic Acid (1), which will be used in peptide synthesis to prepare glycopeptides containing catabolically stable C-linked Neuraminic Acid.
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synthesis of a serine based Neuraminic Acid c glycoside
Journal of Organic Chemistry, 2003Co-Authors: Qun Wang, Robert J. LinhardtAbstract:Cell-surface carbohydrates are classified by the nature of their linkages to the protein as either N-linked or O-linked. O- and N-glycans are involved in a number of important biological functions. These activities can be lost on glycoprotein catabolism when these glycan linkages are enzymatically hydrolyzed. The design and synthesis of novel C-linked glycans should provide catabolically stable glycoproteins useful for understanding and regulating important biological processes. Our efforts are currently directed toward the synthesis of C-glycosides of ulosonic Acids. This paper describes the first synthesis of a serine-based Neuraminic Acid C-glycoside. The protecting group chemistry required for both carbohydrate and peptide syntheses complicates this approach. Different protecting group strategies were investigated for use in the samarium diiodide mediated C-glycosylation reaction. The key elements of our synthetic approach involve the following: (i) the substitution of homoserine for serine in the C-...
Jianhua Qiu - One of the best experts on this subject based on the ideXlab platform.
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Chemoenzymatic Synthesis of N-Acetyl-d-Neuraminic Acid from N-Acetyl-d-Glucosamine by Using the Spore Surface-Displayed N-Acetyl-d-Neuraminic Acid Aldolase
Applied and environmental microbiology, 2011Co-Authors: Chao Gao, Xifeng Zhang, Bin Che, Jianhua Qiu, Fei TaoAbstract:ABSTRACT Chemoenzymatic synthesis of N-acetyl-d-Neuraminic Acid from N-acetyl-d-glucosamine using the spore surface-displayed N-acetyl-d-Neuraminic Acid aldolase at a high concentration (53.9 g liter−1) was achieved in this study. Thus, displaying a target enzyme on the surface of spores might be an alternative for integration of biocatalytic conversion into chemical synthesis.
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Production of N-Acetyl-d-Neuraminic Acid by Use of an Efficient Spore Surface Display System
Applied and environmental microbiology, 2011Co-Authors: Chao Gao, Xifeng Zhang, Bin Che, Jianhua Qiu, Fei TaoAbstract:Production of N-acetyl-D-Neuraminic Acid (Neu5Ac) via biocatalysis is traditionally conducted using isolated enzymes or whole cells. The use of isolated enzymes is restricted by the time-consuming purification process, whereas the application of whole cells is limited by the permeability barrier presented by the microbial cell membrane. In this study, a novel type of biocatalyst, Neu5Ac aldolase presented on the surface of Bacillus subtilis spores, was used for the production of Neu5Ac. Under optimal conditions, Neu5Ac at a high concentration (54.7 g liter⁻¹) and a high yield (90.2%) was obtained under a 5-fold excess of pyruvate over N-acetyl-D-mannosamine. The novel biocatalyst system, which is able to express and immobilize the target enzyme simultaneously on the surface of B. subtilis spores, represents a suitable alternative for value-added chemical production.
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An efficient method for N-acetyl-D-Neuraminic Acid production using coupled bacterial cells with a safe temperature-induced system.
Applied microbiology and biotechnology, 2009Co-Authors: Yinan Zhang, Fei Tao, Jianhua QiuAbstract:N-Acetyl-d-Neuraminic Acid (Neu5Ac) is a precursor for producing many pharmaceutical drugs such as zanamivir which have been used in clinical trials to treat and prevent the infection with influenza virus, such as the avian influenza virus H5N1 and the current 2009 H1N1. Two recombinant Escherichia coli strains capable of expressing N-acetyl-d-glucosamine 2-epimerase and N-acetyl-d-Neuraminic Acid aldolase were constructed based on a highly efficient temperature-responsive expression system which is safe compared to chemical-induced systems and coupled in Neu5Ac production. Carbon sources were optimized for Neu5Ac production, and the concentration effects of carbon sources on the production were investigated. With 2,200 mM pyruvate as carbon source and substrate, 61.9 mM (19.1 g l−1) Neu5Ac was produced from 200 mM N-acetyl-d-glucosamine (GlcNAc) in 36 h by the coupled cells. Our Neu5Ac biosynthetic process is favorable compared with natural product extraction, chemical synthesis, or even many other biocatalysis processes.
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Efficient Whole-Cell Biocatalytic Synthesis of N-Acetyl-D-Neuraminic Acid
Advanced Synthesis & Catalysis, 2007Co-Authors: Jianhua Qiu, Yinan Zhang, Jing Chen, Peng George Wang, Bing Yan, Jing Song, Zixin Deng, Cui QingAbstract:N-Acetyl-D-Neuraminic Acid (Neu5Ac) was efficiently synthesized from lactate and a mixture of N-acetyl-D-glucosamine (GlcNAc) and N-acetyl-D-mannosamine (ManNAc) by whole cells. The biotransformation utilized Escherichia coli cells (Neu5Ac aldolase), Pseudomonas stutzeri cells (lactate oxidase components), GlcNAc/ManNAc and lactate. By this process, 18.32±0.56 g/liter Neu5Ac were obtained from 65.61 ±2.70 g/liter lactate as an initial substrate input. Neu5Ac (98.4 ±0.4% purity, 80.87 ±0.79% recovery yield) was purified by anionic exchange chromatography. Our results demonstrate that the reported Neu5Ac biosynthetic process can compare favorably with natural product extraction or chemical synthesis processes.
Chao Gao - One of the best experts on this subject based on the ideXlab platform.
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Chemoenzymatic Synthesis of N-Acetyl-d-Neuraminic Acid from N-Acetyl-d-Glucosamine by Using the Spore Surface-Displayed N-Acetyl-d-Neuraminic Acid Aldolase
Applied and environmental microbiology, 2011Co-Authors: Chao Gao, Xifeng Zhang, Bin Che, Jianhua Qiu, Fei TaoAbstract:ABSTRACT Chemoenzymatic synthesis of N-acetyl-d-Neuraminic Acid from N-acetyl-d-glucosamine using the spore surface-displayed N-acetyl-d-Neuraminic Acid aldolase at a high concentration (53.9 g liter−1) was achieved in this study. Thus, displaying a target enzyme on the surface of spores might be an alternative for integration of biocatalytic conversion into chemical synthesis.
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Production of N-Acetyl-d-Neuraminic Acid by Use of an Efficient Spore Surface Display System
Applied and environmental microbiology, 2011Co-Authors: Chao Gao, Xifeng Zhang, Bin Che, Jianhua Qiu, Fei TaoAbstract:Production of N-acetyl-D-Neuraminic Acid (Neu5Ac) via biocatalysis is traditionally conducted using isolated enzymes or whole cells. The use of isolated enzymes is restricted by the time-consuming purification process, whereas the application of whole cells is limited by the permeability barrier presented by the microbial cell membrane. In this study, a novel type of biocatalyst, Neu5Ac aldolase presented on the surface of Bacillus subtilis spores, was used for the production of Neu5Ac. Under optimal conditions, Neu5Ac at a high concentration (54.7 g liter⁻¹) and a high yield (90.2%) was obtained under a 5-fold excess of pyruvate over N-acetyl-D-mannosamine. The novel biocatalyst system, which is able to express and immobilize the target enzyme simultaneously on the surface of B. subtilis spores, represents a suitable alternative for value-added chemical production.
Qun Wang - One of the best experts on this subject based on the ideXlab platform.
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Chemoenzymatic synthesis of Neuraminic Acid containing C-glycoside polymers.
Organic letters, 2003Co-Authors: Qun Wang, Jonathan S. Dordick, Robert J. LinhardtAbstract:Two Neuraminic Acid-based, C-glycoside polymers were synthesized. Preliminary studies on one of these polymers showed potent neuraminidase inhibitory activity, suggesting potential utility as an antipathogenic surface coating for the preparation of antimicrobial biomaterials.
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Synthesis of a serine-based Neuraminic Acid C-glycoside.
The Journal of organic chemistry, 2003Co-Authors: Qun Wang, Robert J. LinhardtAbstract:Cell-surface carbohydrates are classified by the nature of their linkages to the protein as either N-linked or O-linked. O- and N-glycans are involved in a number of important biological functions. These activities can be lost on glycoprotein catabolism when these glycan linkages are enzymatically hydrolyzed. The design and synthesis of novel C-linked glycans should provide catabolically stable glycoproteins useful for understanding and regulating important biological processes. Our efforts are currently directed toward the synthesis of C-glycosides of ulosonic Acids. This paper describes the first synthesis of a serine-based Neuraminic Acid C-glycoside. The protecting group chemistry required for both carbohydrate and peptide syntheses complicates this approach. Different protecting group strategies were investigated for use in the samarium diiodide mediated C-glycosylation reaction. The key elements of our synthetic approach involve the following: (i) the substitution of homoserine for serine in the C-glycosylation reaction to introduce a carbon in place of the O-glycosidic oxygen, (ii) the use of benzyloxycarbonyl as a homoserine protecting group, compatible with samarium diiodide mediated C-glycosylation reaction, and (iii) the reduction of the carbonyl group in homoserine early in the synthesis to improve C-glycosylation yield and to avoid lactone formation. Using this combined approach, we prepared 4-O-acetyl-4-[2-C-(1-methyl 5-acetamido 4,7,8,9-tetra-O-acetyl-2,6-anhydro-3,5-dideoxy-d-erythro-l-manno-nononate)]-2S-(benzyloxycarbonyl)amino-1-carboxylic Acid (1), which will be used in peptide synthesis to prepare glycopeptides containing catabolically stable C-linked Neuraminic Acid.
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synthesis of a serine based Neuraminic Acid c glycoside
Journal of Organic Chemistry, 2003Co-Authors: Qun Wang, Robert J. LinhardtAbstract:Cell-surface carbohydrates are classified by the nature of their linkages to the protein as either N-linked or O-linked. O- and N-glycans are involved in a number of important biological functions. These activities can be lost on glycoprotein catabolism when these glycan linkages are enzymatically hydrolyzed. The design and synthesis of novel C-linked glycans should provide catabolically stable glycoproteins useful for understanding and regulating important biological processes. Our efforts are currently directed toward the synthesis of C-glycosides of ulosonic Acids. This paper describes the first synthesis of a serine-based Neuraminic Acid C-glycoside. The protecting group chemistry required for both carbohydrate and peptide syntheses complicates this approach. Different protecting group strategies were investigated for use in the samarium diiodide mediated C-glycosylation reaction. The key elements of our synthetic approach involve the following: (i) the substitution of homoserine for serine in the C-...
