The Experts below are selected from a list of 84261 Experts worldwide ranked by ideXlab platform
Shuichi Takayama - One of the best experts on this subject based on the ideXlab platform.
-
membraneless compartmentalization facilitates enzymatic cascade reactions and reduces Substrate Inhibition
ACS Applied Materials & Interfaces, 2018Co-Authors: Taisuke Kojima, Shuichi TakayamaAbstract:Living cells possess membraneless organelles formed by liquid–liquid phase separation. With the aim of better understanding the general functions of membraneless microcompartments, this paper constructs acellular multicompartment reaction systems using an aqueous multiphase system. Membraneless coacervate droplets are placed within a molecularly crowded environment, where a larger dextran (DEX) droplet is submerged in a polyethylene glycol (PEG) solution. The coacervate droplets are capable of sequestering reagents and enzymes with a long retention time, and demonstrate multistep cascading reactions through the liquid–liquid interfaces. The ability to change phase dynamics is also demonstrated through salt-mediated dissolution of coacervate droplets, which leads to the release and mixing of separately sequestered reagents and enzymes. Finally, as phase-separated materials in membraneless organelles are often Substrates and Substrate analogues for the enzymes sequestered or excluded in the organelles, this...
-
Membraneless Compartmentalization Facilitates Enzymatic Cascade Reactions and Reduces Substrate Inhibition
2018Co-Authors: Taisuke Kojima, Shuichi TakayamaAbstract:Living cells possess membraneless organelles formed by liquid–liquid phase separation. With the aim of better understanding the general functions of membraneless microcompartments, this paper constructs acellular multicompartment reaction systems using an aqueous multiphase system. Membraneless coacervate droplets are placed within a molecularly crowded environment, where a larger dextran (DEX) droplet is submerged in a polyethylene glycol (PEG) solution. The coacervate droplets are capable of sequestering reagents and enzymes with a long retention time, and demonstrate multistep cascading reactions through the liquid–liquid interfaces. The ability to change phase dynamics is also demonstrated through salt-mediated dissolution of coacervate droplets, which leads to the release and mixing of separately sequestered reagents and enzymes. Finally, as phase-separated materials in membraneless organelles are often Substrates and Substrate analogues for the enzymes sequestered or excluded in the organelles, this paper explores the interaction between DEX and dextranase, an enzyme that hydrolyzes DEX. The results reveal that dextranase suffers from Substrate Inhibition when partitioned directly in a DEX phase but that this Inhibition can be mitigated and reactions greatly accelerated by compartmentalization of dextranase inside a coacervate droplet that is adjacent to, but phase-separated from, the DEX phase. The insight that compartmentalization of enzymes can accelerate reactions by mitigating Substrate Inhibition is particularly novel and is an example where artificial membraneless organelle-like systems may provide new insights into physiological cell functions
Sang Yup Lee - One of the best experts on this subject based on the ideXlab platform.
-
enhanced succinic acid production by mannheimia employing optimal malate dehydrogenase
Nature Communications, 2020Co-Authors: Jung Ho Ahn, Hogyun Seo, Woojin Park, Jihye Seok, Jong An Lee, Wonjun Kim, Gi Bae Kim, Kyungjin Kim, Sang Yup LeeAbstract:Succinic acid (SA), a dicarboxylic acid of industrial importance, can be efficiently produced by metabolically engineered Mannheimia succiniciproducens. Malate dehydrogenase (MDH) is one of the key enzymes for SA production, but has not been well characterized. Here we report biochemical and structural analyses of various MDHs and development of hyper-SA producing M. succiniciproducens by introducing the best MDH. Corynebacterium glutamicum MDH (CgMDH) shows the highest specific activity and least Substrate Inhibition, whereas M. succiniciproducens MDH (MsMDH) shows low specific activity at physiological pH and strong uncompetitive Inhibition toward oxaloacetate (ki of 67.4 and 588.9 μM for MsMDH and CgMDH, respectively). Structural comparison of the two MDHs reveals a key residue influencing the specific activity and susceptibility to Substrate Inhibition. A high-inoculum fed-batch fermentation of the final strain expressing cgmdh produces 134.25 g L−1 of SA with the maximum productivity of 21.3 g L−1 h−1, demonstrating the importance of enzyme optimization in strain development. Malate dehydrogenase (MDH) is one of the key enzymes for succinic acid (SA) bioproduction. Here, the authors report biochemical and structural analyses of various MDHs to reveal amino acids influencing the specific activity and susceptibility to Substrate Inhibition, and achieve industrial-level SA production.
Hogyun Seo - One of the best experts on this subject based on the ideXlab platform.
-
enhanced succinic acid production by mannheimia employing optimal malate dehydrogenase
Nature Communications, 2020Co-Authors: Jung Ho Ahn, Hogyun Seo, Woojin Park, Jihye Seok, Jong An Lee, Wonjun Kim, Gi Bae Kim, Kyungjin Kim, Sang Yup LeeAbstract:Succinic acid (SA), a dicarboxylic acid of industrial importance, can be efficiently produced by metabolically engineered Mannheimia succiniciproducens. Malate dehydrogenase (MDH) is one of the key enzymes for SA production, but has not been well characterized. Here we report biochemical and structural analyses of various MDHs and development of hyper-SA producing M. succiniciproducens by introducing the best MDH. Corynebacterium glutamicum MDH (CgMDH) shows the highest specific activity and least Substrate Inhibition, whereas M. succiniciproducens MDH (MsMDH) shows low specific activity at physiological pH and strong uncompetitive Inhibition toward oxaloacetate (ki of 67.4 and 588.9 μM for MsMDH and CgMDH, respectively). Structural comparison of the two MDHs reveals a key residue influencing the specific activity and susceptibility to Substrate Inhibition. A high-inoculum fed-batch fermentation of the final strain expressing cgmdh produces 134.25 g L−1 of SA with the maximum productivity of 21.3 g L−1 h−1, demonstrating the importance of enzyme optimization in strain development. Malate dehydrogenase (MDH) is one of the key enzymes for succinic acid (SA) bioproduction. Here, the authors report biochemical and structural analyses of various MDHs to reveal amino acids influencing the specific activity and susceptibility to Substrate Inhibition, and achieve industrial-level SA production.
Jung Ho Ahn - One of the best experts on this subject based on the ideXlab platform.
-
enhanced succinic acid production by mannheimia employing optimal malate dehydrogenase
Nature Communications, 2020Co-Authors: Jung Ho Ahn, Hogyun Seo, Woojin Park, Jihye Seok, Jong An Lee, Wonjun Kim, Gi Bae Kim, Kyungjin Kim, Sang Yup LeeAbstract:Succinic acid (SA), a dicarboxylic acid of industrial importance, can be efficiently produced by metabolically engineered Mannheimia succiniciproducens. Malate dehydrogenase (MDH) is one of the key enzymes for SA production, but has not been well characterized. Here we report biochemical and structural analyses of various MDHs and development of hyper-SA producing M. succiniciproducens by introducing the best MDH. Corynebacterium glutamicum MDH (CgMDH) shows the highest specific activity and least Substrate Inhibition, whereas M. succiniciproducens MDH (MsMDH) shows low specific activity at physiological pH and strong uncompetitive Inhibition toward oxaloacetate (ki of 67.4 and 588.9 μM for MsMDH and CgMDH, respectively). Structural comparison of the two MDHs reveals a key residue influencing the specific activity and susceptibility to Substrate Inhibition. A high-inoculum fed-batch fermentation of the final strain expressing cgmdh produces 134.25 g L−1 of SA with the maximum productivity of 21.3 g L−1 h−1, demonstrating the importance of enzyme optimization in strain development. Malate dehydrogenase (MDH) is one of the key enzymes for succinic acid (SA) bioproduction. Here, the authors report biochemical and structural analyses of various MDHs to reveal amino acids influencing the specific activity and susceptibility to Substrate Inhibition, and achieve industrial-level SA production.
-
Enhanced succinic acid production by Mannheimia employing optimal malate dehydrogenase
'Springer Science and Business Media LLC', 2020Co-Authors: Jung Ho Ahn, Jong An Lee, Seo Hogyun, Park Woojin, Seok Jihye, Kim, Won Jun, Kim, Gi Bae, Kim Kyung-jin, Lee, Sang YupAbstract:Succinic acid (SA), a dicarboxylic acid of industrial importance, can be efficiently produced by metabolically engineered Mannheimia succiniciproducens. Malate dehydrogenase (MDH) is one of the key enzymes for SA production, but has not been well characterized. Here we report biochemical and structural analyses of various MDHs and development of hyper-SA producing M. succiniciproducens by introducing the best MDH. Corynebacterium glutamicum MDH (CgMDH) shows the highest specific activity and least Substrate Inhibition, whereas M. succiniciproducens MDH (MsMDH) shows low specific activity at physiological pH and strong uncompetitive Inhibition toward oxaloacetate (ki of 67.4 and 588.9 μM for MsMDH and CgMDH, respectively). Structural comparison of the two MDHs reveals a key residue influencing the specific activity and susceptibility to Substrate Inhibition. A high-inoculum fed-batch fermentation of the final strain expressing cgmdh produces 134.25 g L of SA with the maximum productivity of 21.3 g L h, demonstrating the importance of enzyme optimization in strain development
Ki Seog Lee - One of the best experts on this subject based on the ideXlab platform.
-
structural insight into the Substrate Inhibition mechanism of nadp dependent succinic semialdehyde dehydrogenase from streptococcus pyogenes
Biochemical and Biophysical Research Communications, 2015Co-Authors: Eun Hyuk Jang, Seong Ah Park, Young Min Chi, Ki Seog LeeAbstract:Abstract Succinic semialdehyde dehydrogenases (SSADHs) are ubiquitous enzymes that catalyze the oxidation of succinic semialdehyde (SSA) to succinic acid in the presence of NAD(P) + , and play an important role in the cellular mechanisms including the detoxification of accumulated SSA or the survival in conditions of limited nutrients. Here, we report the inhibitory properties and two crystal structures of SSADH from Streptococcus pyogenes (SpSSADH) in a binary (ES) complex with SSA as the Substrate and a ternary (ESS) complex with the Substrate SSA and the inhibitory SSA, at 2.4 A resolution for both structures. Analysis of the kinetic inhibitory parameters revealed significant Substrate Inhibition in the presence of NADP + at concentrations of SSA higher than 0.02 mM, which exhibited complete uncompetitive Substrate Inhibition with the Inhibition constant ( K i ) value of 0.10 ± 0.02 mM. In ES-complex of SpSSADH, the SSA showed a tightly bound bent form nearby the catalytic residues, which may be caused by reduction of the cavity volume for Substrate binding, compared with other SSADHs. Moreover, structural comparison of ESS-complex with a binary complex with NADP + of SpSSADH indicated that the Substrate Inhibition was induced by the binding of inhibitory SSA in the cofactor-binding site, instead of NADP + . Our results provide first structure-based molecular insights into the Substrate Inhibition mechanism of SpSSADH as the Gram-positive bacterial SSADH.
-
kinetic characterization and molecular modeling of nad p dependent succinic semialdehyde dehydrogenase from bacillus subtilis as an ortholog ynei
Journal of Microbiology and Biotechnology, 2014Co-Authors: Seong Ah Park, Ye Song Park, Ki Seog LeeAbstract:Succinic semialdehyde dehydrogenase (SSADH) catalyzes the oxidation of succinic semialdehyde (SSA) into succinic acid in the final step of γ-aminobutyric acid degradation. Here, we characterized Bacillus subtilis SSADH (BsSSADH) regarding its cofactor discrimination and Substrate Inhibition. BsSSADH showed similar values of the catalytic efficiency (kcat/Km) in both NAD(+) and NADP(+) as cofactors, and exhibited complete uncompetitive Substrate Inhibition at higher SSA concentrations. Further analyses of the sequence alignment and homology modeling indicated that the residues of catalytic and cofactor-binding sites in other SSADHs were highly conserved in BsSSADH.
