Pyruvate,orthophosphate dikinase from Acetobacter aceti |
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Authors: | Schwitzguebel J -P Ettlinger L |
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Institution: | (1) Eidgenössische Technische Hochschule, ETH-Zentrum, Mikrobiologisches Institut, CH-8092 Zürich, Switzerland;(2) Present address: Department of Botany, Imperial College, SW7 2BB London, England |
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Abstract: | A pyruvate, orthophosphate dikinase (EC 2.7.9.1) has been isolated from Acetobacter aceti grown on pyruvate as the only source of carbon and energy. The enzyme was purified 65-fold, and its molecular weight was determined to be about 330,000 by gel filtration.The optimum pH was 8.0 in the forward direction phosphoenolpyruvate (PEP) formation] and 7.1 for the backward reaction (pyruvate production). In both directions Mg2+ was required (forward K
m
1.70 mM; reverse K
m
0.87 mM) and no other divalent cation was able to replace it. The K
m
values for pyruvate, ATP, and Pi were 27 M, 0.20 mM, and 0.83 mM, respectively, in the forward direction. The K
m
values for PEP, AMP, and PPi were 0.13 mM, 6 M, and 62 M, respectively, for the reverse reaction. The substrate-product pairs pyruvate-PEP, ATP-AMP, Pi-PPi were competitive inhibitors to each other in both directions. These product inhibition studies suggest for the enzyme from A. aceti nonclassical three-site Tri (Uni Uni) Ping-Pong kinetics.Abbreviations PEP
phosphoenolpyruvate
- OAA
oxaloacetate
- MW
molecular weight
- SDS
sodium dodecyl sulphate
- TEMG buffer
50 mM Tris-HCl, pH 7.5, 1 mM EDTA, 5 mM MgCl2, 1 mM glutathione |
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Keywords: | Acetobacter aceti Pyruvate metabolism Pyruvate orthophosphate dikinase |
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