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31	Effect of Tris, MOPS, and phosphate buffers on the hydrolysis of polyethylene terephthalate films by polyester hydrolases Schmidt, Juliane, Wei, Ren, Oeser, Thorsten, Belisário-Ferrari, Matheus Regis, Barth, Markus, Then, Johannes, Zimmermann, Wolfgang 21 July 2016 (has links) (PDF) The enzymatic degradation of polyethylene terephthalate (PET) occurs at mild reaction conditions and may find applications in environmentally friendly plastic waste recycling processes. The hydrolytic activity of the homologous polyester hydrolases LC cutinase (LCC) from a compost metagenome and TfCut2 from Thermobifida fusca KW3 against PET films was strongly influenced by the reaction medium buffers tris(hydroxymethyl)aminomethane (Tris), 3-(N-morpholino)propanesulfonic acid (MOPS), and sodium phosphate. LCC showed the highest initial hydrolysis rate of PET films in 0.2 M Tris, while the rate of TfCut2 was 2.1-fold lower at this buffer concentration. At a Tris concentration of 1 M, the hydrolysis rate of LCC decreased by more than 90% and of TfCut2 by about 80%. In 0.2 M MOPS or sodium phosphate buffer, no significant differences in the maximum initial hydrolysis rates of PET films by both enzymes were detected. When the concentration of MOPS was increased to 1 M, the hydrolysis rate of LCC decreased by about 90%. The activity of TfCut2 remained low compared to the increasing hydrolysis rates observed at higher concentrations of sodium phosphate buffer. In contrast, the activity of LCC did not change at different concentrations of this buffer. An inhibition study suggested a competitive inhibition of TfCut2 and LCC by Tris and MOPS. Molecular docking showed that Tris and MOPS interfered with the binding of the polymeric substrate in a groove located at the protein surface. A comparison of the Ki values and the average binding energies indicated MOPS as the stronger inhibitor of the both enzymes. 3-(N-Morpholino)propansulfonsäure Biokatalyse Polyester Hydrolase Polyethylenterephthalat (PET) Tris(hydroxymethyl)-aminomethan (TRIS) 3-(N-morpholino)propanesulfonic acid biocatalysis inhibition polyester hydrolase polyethylene terephthalate Tris ddc:540
32	Biochemische und strukturelle Untersuchungen der Kohlenmonoxid-Dehydrogenasen CODH-II und CODH-V aus Carboxydothermus hydrogenoformans Fesseler, Jochen Martin 24 July 2015 (has links) Eine Vielzahl strikt anaerober Organismen verwendet den reduktiven Acetyl-CoA-Weg zum autotrophen Wachstum mit Kohlenmonoxid als einziger Kohlenstoffquelle. Die Kohlenmonoxid-Dehydrogenase (CODH) ist das Schlüsselenzym dieses Stoffwechselweges und katalysiert die Oxidation von CO mit Raten von bis zu 31,000 s–1 und die Reduktion von CO2 mit bis zu 12 s–1 an einem [Ni4Fe4S-OHx]-Cluster (C-Cluster). Das Genom des thermophilen und hydrogenogenen Bakteriums Carboxydothermus hydrogenoformans enthält insgesamt fünf Gene, die für CODHs kodieren. Anhand der Genumgebung wurden dabei unterschiedliche Rollen für die einzelnen CODHs vorgeschlagen. Für ein besseres Verständnis der molekularen Prozesse in der Katalyse, wurden CODH-IICh und -VCh heterolog in Escherichia coli produziert und biochemisch und strukturell charakterisiert. / A variety of strict anaerobic organisms employ the reductive acetyl-CoA path for autotrophic growth, using carbon monoxide as sole carbon source. Carbon monoxide dehydrogenase (CODH) is the key enzyme of the path and catalyzes CO oxidation with rates of 31,000 s–1 and CO2 reduction with rates of 12 s–1 at a [Ni4Fe4S-OHx] cluster (cluster C). The genome of the thermophilic and hydrogenogenic bacterium Carboxydothermus hydrogenoformans contains five copies of genes coding for the catalytic subunit of a CODH. According to the gene environment, different physiological roles for the individual CODHs were proposed. To compare their respective structure and catalytic function, CODH-IICh and -VCh were heterologously produced in Escherichia coli and biochemically and structurally investigated. Biokatalyse CO2-Aktivierung Strukturbiologie Röntgenstrukturanalyse Biocatalysis CO2 activation structural biology X-ray crystallography 570 Biowissenschaften, Biologie 32 Biologie XD 5804 ddc:570
33	Advanced Insights into Catalytic and Structural Features of the Zinc-Dependent Alcohol Dehydrogenase from Thauera aromatica Stark, Frances, Loderer, Christoph, Petchey, Mark, Grogan, Gideon, Ansorge-Schumacher, Marion B. 08 April 2024 (has links) The asymmetric reduction of ketones to chiral hydroxyl compounds by alcohol dehydrogenases (ADHs) is an established strategy for the provision of valuable precursors for fine chemicals and pharmaceutics. However, most ADHs favor linear aliphatic and aromatic carbonyl compounds, and suitable biocatalysts with preference for cyclic ketones and diketones are still scarce. Among the few candidates, the alcohol dehydrogenase from Thauera aromatica (ThaADH) stands out with a high activity for the reduction of the cyclic α-diketone 1,2-cyclohexanedione to the corresponding α-hydroxy ketone. This study elucidates catalytic and structural features of the enzyme. ThaADH showed a remarkable thermal and pH stability as well as stability in the presence of polar solvents. A thorough description of the substrate scope combined with the resolution and description of the crystal structure, demonstrated a strong preference of ThaADH for cyclic α-substituted cyclohexanones, and indicated structural determinants responsible for the unique substrate acceptance. info:eu-repo/classification/ddc/540 ddc:540
34	Metagenombasierte Isolierung und biochemische Charakterisierung neuartiger stereospezifischer Lipasen für biokatalytische Anwendungen / Metagenome based isolation and biochemical characterization of novel stereospecific lipases for biocatalytical applications Elend, Christian 01 November 2006 (has links) No description available. 570 Biowissenschaften, Biologie Mathematics and Computer Science Metagenom Lipase Biokatalyse Kälteaktive Enzyme Stereospezifität Ibuprofen Menthylacetat DNA-Microarray metagenome biocatalysis cold-active enzymes stereospecificity ibuprofen menthyl acetate DNA-microarray 42.13 42.30 58.30 WUE000 WUO400 WUV000
35	A disulfide bridge in the calcium binding site of a polyester hydrolase increases its thermal stability and activity against polyethylene terephthalate Then, Johannes, Wei, Ren, Oeser, Thorsten, Gerdts, André, Schmidt, Juliane, Barth, Markus, Zimmermann, Wolfgang January 2016 (has links) Elevated reaction temperatures are crucial for the efficient enzymatic degradation of polyethylene terephthalate (PET). A disulfide bridge was introduced to the polyester hydrolase TfCut2 to substitute its calcium binding site. The melting point of the resulting variant increased to 94.7°C (wild-type TfCut2: 69.8 °C) and its half-inactivation temperature to 84.6 °C (TfCut2: 67.3 °C). The variant D204C-E253C-D174R obtained by introducing further mutations at vicinal residues showed a temperature optimum between 75 and 80 °C compared to 65 and 70 °C of the wild-type enzyme. The variant caused a weight loss of PET films of 25.0 +/- 0.8% (TfCut2: 0.3 +/-0.1%) at 70 °C after a reaction time of 48 h. The results demonstrate that a highly efficient and calcium-independent thermostable polyester hydrolase can be obtained by replacing its calcium binding site with a disulfide bridge. info:eu-repo/classification/ddc/540 ddc:540 info:eu-repo/classification/ddc/570 ddc:570
36	Effect of Tris, MOPS, and phosphate buffers on the hydrolysis of polyethylene terephthalate films by polyester hydrolases Schmidt, Juliane, Wei, Ren, Oeser, Thorsten, Belisário-Ferrari, Matheus Regis, Barth, Markus, Then, Johannes, Zimmermann, Wolfgang January 2016 (has links) The enzymatic degradation of polyethylene terephthalate (PET) occurs at mild reaction conditions and may find applications in environmentally friendly plastic waste recycling processes. The hydrolytic activity of the homologous polyester hydrolases LC cutinase (LCC) from a compost metagenome and TfCut2 from Thermobifida fusca KW3 against PET films was strongly influenced by the reaction medium buffers tris(hydroxymethyl)aminomethane (Tris), 3-(N-morpholino)propanesulfonic acid (MOPS), and sodium phosphate. LCC showed the highest initial hydrolysis rate of PET films in 0.2 M Tris, while the rate of TfCut2 was 2.1-fold lower at this buffer concentration. At a Tris concentration of 1 M, the hydrolysis rate of LCC decreased by more than 90% and of TfCut2 by about 80%. In 0.2 M MOPS or sodium phosphate buffer, no significant differences in the maximum initial hydrolysis rates of PET films by both enzymes were detected. When the concentration of MOPS was increased to 1 M, the hydrolysis rate of LCC decreased by about 90%. The activity of TfCut2 remained low compared to the increasing hydrolysis rates observed at higher concentrations of sodium phosphate buffer. In contrast, the activity of LCC did not change at different concentrations of this buffer. An inhibition study suggested a competitive inhibition of TfCut2 and LCC by Tris and MOPS. Molecular docking showed that Tris and MOPS interfered with the binding of the polymeric substrate in a groove located at the protein surface. A comparison of the Ki values and the average binding energies indicated MOPS as the stronger inhibitor of the both enzymes. info:eu-repo/classification/ddc/540 ddc:540

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