ISSN:
1432-072X
Keywords:
Acetobacter aceti
;
Pyruvate metabolism
;
Pyruvate, orthophosphate dikinase
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
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 μM, 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 μM, and 62 μM, 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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00408052
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