ISSN:
1432-072X
Keywords:
Acetobacter aceti
;
Pyruvate metabolism
;
PEP carboxylation
;
PEP carboxylase
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract In Acetobacter aceti growing on pyruvate as the only source of carbon and energy, oxaloacetate (OAA) is produced by a phosphoenolpyruvate (PEP) carboxylase (EC 4.1.1.31). The enzyme was purified 122-fold and a molecular weight of about 380,000 was estimated by gel filtration. The optimum pH was 7.5 and the K m values for PEP and NaHCO3 were 0.49 mM and about 3 mM, respectively. The enzyme needed a divalent cation; the K m for Mn2+, Co2+ and Mg2+ were 0.12, 0.26 and 0.77 mM, respectively. Maximal activity was only obtained with Mg2+. Mn2+ and Co2+ became inhibitory at high concentrations. The activity was inhibited by succinate and, to a lesser extent, by fumarate, citrate, α-ketoglutarate, aspartate and glutamate. As compared with the corresponding enzyme from A. xylinum, the PEP carboxylase of A. aceti showed the following differences: a) It had an absolute requirement for acetyl CoA (K a 0.18 mM) or propionyl CoA (K a 0.2 mM). b) It was not affected by ADP. c) It was sensitive to thiol blocking agents.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00408053
Permalink
