ISSN:
1432-072X
Keywords:
Oxalate Accumulation
;
Aspergillus
;
Citrate Degradation
;
Tricarboxylic Acid Cycle
;
Enzyme Synthesis
;
Fluoroacetate
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Carbon-14 was incorporated into oxalate and CO2 from either citrate-1,5-14C, succinate-1,4-14C, or fumarate-1,4-14C by cultures of Aspergillus niger pregrown on a medium which contained glucose as the sole carbon source and which did not allow citrate accumulation. In cell-free extracts of mycelium forming oxalate and CO2 from added citrate the following enzymes of the tricarboxylic acid (TCA) cycle were identified: citrate synthase (CE 4.1.3.7), aconitate hydratase (EC 4.2.1.3), NAD- and NADP-dependent isocitrate dehydrogenase (EC 1.1.1.41, 1.1.1.42), (α-oxoglutarate dehydrogenase (EC 1.2.4.2), succinate dehydrogenase (EC1.3.99.1), fumarate hydratase (EC 4.2.1.2), and malate dehydrogenase (EC 1.1.1.37). The in vitro activity of aconitate hydratase and of NADP-dependent isocitrate dehydrogenase was shown to be almost identical to the rate of in vivo degradation of citrate or to exceed this rate. The degradation of citrate to oxalate was inhibited completely by 9 mM fluoroacetate. It is concluded that the TCA cycle is involved in the formation of oxalate from citrate.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00447318
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