NADP+-dependent acetaldehyde dehydrogenase from Zymomonas mobilis |
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Authors: | Thomas Barthel Rainer Jonas Hermann Sahm |
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Institution: | (1) Institut für Biotechnologie 1 der Kernforschungsanlage Jülich, Postfach 1913, D-5170 Jülich, Federal Republic of Germany;(2) Present address: Depto. Bioquimica, Universidade Federal de Pernambuco, Cidade Universitaria, BR-50730 Recife, Brazil |
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Abstract: | An NADP+-linked acetaldehyde dehydrogenase (EC 1.2.1.4) from the ethanol producing bacterium Zymomonas mobilis was purified 180-fold to homogeneity. The enzyme is a cytosolic protein with an isoelectric point of 8.0 and has an apparent molecular weight of 210000. It showed a single band in sodium dodecylsulfate gel electrophoresis with a molecular weight of 55000, which indicates that it consists of four probably identical subunits. The apparent K
m values for the substrate acetaldehyde were 57 M and for the cosubstrate NADP+ 579 M. The enzyme was almost inactive with NAD+ as cofactor. Several other aldehydes besides acetaldehyde were accepted as a substrate but not formaldehyde or trichloroacetaldehyde. In anaerobically grown cells of Zymomonas mobilis the enzyme showed a specific activity of 0.035 U/mg protein but its specific activity could be increased up to 0.132 U/mg protein by adding acetaldehyde to the medium during the exponential growth phase or up to 0.284 U/mg protein when cells were grown under aeration. The physiological role of the enzyme is discussed.Abbreviations ALD-DH
acetaldehyde dehydrogenases from Z. mobilis
- DTT
dithiothreitol
- MES
2-(N-morpholino)ethanesulfonic acid
- MOPS
3-(N-morpholino)propanesulfonic acid
- SDS
sodium dodecylsulfate
Dedicated to Prof. Dr. H.-G. Schlegel, Universität Göttingen, on the occasion of his 65th birthday |
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Keywords: | NADP+-Linked acetaldehyde dehydrogenase Zymomonas mobilis Purification Molecular weight Isoelectric point K
m values Aerobic growth Induction of enzyme activity by acetaldehyde Substrate specifity |
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