30 resultados para Dodecyl-sulfate Micelles
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Biochemical and Biophysical Research Communications 308 (2003) 73–78
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Biophysical Chemistry 110 (2004) 83–92
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The enzyme hydrogenase isolated from the sulphate reducing anaerobic bacterium Desulfovibrio gigas was encapsulated in reverse micelles of AOT–water–isooctane. The enzyme ability to consume molecular hydrogen was studied as a function of the micelle size (given by Wo = [H2O]/[organic solvent]). A peak of catalytic activity was obtained for Wo = 18, a micelle size theoretically fitting the heterodimeric hydrogenase molecule. At this Wo value, the recorded catalytic activity was slightly higher than in a buffer system(Kcat = 169.43 s−1 against the buffer value of 151 s−1). The optimal buffer used to encapsulate the enzyme was found to be imidazole 50 mM, pH 9.0. The molecular hydrogen production activity was also tested in this reverse micelle medium.
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The [NiFe] hydrogenase from Desulfovibrio vulgaris Hildenborough was isolated from the cytoplasmic membranes and characterized by EPR spectroscopy. It has a total molecular mass of 98.7 kDa (subunits of 66.4 and 32.3 kDa), and contains 1 nickel and 12 Fe atoms per heterodimer. The catalytic activities for hydrogen consumption and production were determined to be 174 and 89 umol H2 min-1 mg -1, respectively. As isolated, under aerobic conditions, this hydrogenase exhibits EPR signals characteristic of the nickel centers in [NiFe] hydrogenases (Ni-A signal at gx,y,z=2.32, 2.23 and ~2.0 and Ni-B signal at gx,y,z=2.33, 2.16 and ~2.0) as well as an intense quasi-isotropic signal centered at g=2.02 due to the oxidized [3Fe-4S] center. The redox profile under hydrogen atmosphere is remarkably similar to that of other [NiFe] hydrogenases. The signals observed for the oxidized state disappear, first being substituted by the Ni-C type signal (gx,y,z=2.19, 2.14, ~2.01), which upon long incubation under hydrogen yields the split Ni-C signal due to interaction with the reduced [4Fe-4S] centers.
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Dissertação apresentada para a obtenção do Grau de Doutor em Bioquímica, especialidade Bioquímica-Física pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia
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Dissertation presented to obtain the Ph.D degree in Biochemistry
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Acta Crystallogr Sect F Struct Biol Cryst Commun. 2009 Sep 1;65(Pt 9):926-9
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Acta Crystallogr Sect F Struct Biol Cryst Commun. 2008 Jul 1;64(Pt 7):593-5
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Bioinorganic Chemistry and Applications Volume 3 (2005), Issue 1-2, Pages 81-91
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Acc. Chem. Res., 2006, 39 (10), pp 788–796 DOI: 10.1021/ar050104k
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J Biol Inorg Chem (2004) 9: 145–151 DOI 10.1007/s00775-003-0506-z
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Dissertação para a obtenção de grau de doutor em Bioquímica pelo Instituto de Tecnologia Química e Biológica. Universidade Nova de Lisboa.
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Eur. J. Biochem. 270, 3904–3915 (2003)
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Dissertação apresentada para a obtenção do Grau de Doutor em Química, especialidade em Química-Física, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia
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Dissertação apresentada para obtenção do grau de Doutor em Bioquímica,especialidade Bioquímica-Física, pela Universidade Nova de Lisboa, Faculdade de Cincias e Tecnologia