Regulation of the TCA and Glyoxylate Cycles in Brevibacterium flavum

Ozaki, Hachiro; Shiio, Isamu

doi:10.1093/oxfordjournals.jbchem.a129148

Cited by 97 publications

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“…Concerted inhibition of the NADP+-specific isocitrate dehydrogenase by glyoxylate and oxalacetate has been reported for the enzyme from a number of sources (15,(17)(18)(19) and has been related to the operation of the tricarboxylic acid and glyoxylic acid cycles. This inhibition, however, has also been found in the enzyme from pig heart (19), even though mammalian systems do not possess the glyoxylate cycle.…”

Section: Discussionmentioning

confidence: 99%

“…Nicotiniamide adenine dintucleotide plhosphate-specific isocitrate dehydrogenase was extracted from etiolated pea (Pisurn satirum L.) seedlings and was purified 65- (15,(17)(18)(19). The importance of these findings when considering metabolic regulation is difficult to assess since the function of the enzyme in the cell of eucaryotic organisms which also possess the NAD+-specific enzyme is not known.…”

Section: Introductionmentioning

confidence: 99%

“…It has been sug-gested that the principal regulation of the enzyme is by the ratio of NADH to NAD+ (5,9,10 (23). The enzyme from bacterial (14,18,19), protozoan (15)(16)(17) and pig heart sources (2, 3) has recently been studied and in all cases has shown to have normal kinetics with respect to the substrates. In contrast to the NAD+-specific enzyme it readily catalyzes the reactions both in the forward direction (NADP+ reduction) and in the reverse direction.…”

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confidence: 99%

“…It has been suggested that the NADP+-specific enzyme is regulated by the concentration of ATP in the cell (14,16). There are also indications that there is a concerted inhibition when glyoxylate and oxalacetate are added together (15,(17)(18)(19). The importance of these findings when considering metabolic regulation is difficult to assess since the function of the enzyme in the cell of eucaryotic organisms which also possess the NAD+-specific enzyme is not known.…”

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confidence: 99%

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Nicotinamide Adenine Dinucleotide Phosphate-specific Isocitrate Dehydrogenase from a Higher Plant

Omran

Dennis

1971

Plant Physiol.

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Nicotiniamide adenine dintucleotide plhosphate-specific isocitrate dehydrogenase was extracted from etiolated pea (Pisurn satirum L.) seedlings and was purified 65- (15,(17)(18)(19). The importance of these findings when considering metabolic regulation is difficult to assess since the function of the enzyme in the cell of eucaryotic organisms which also possess the NAD+-specific enzyme is not known. It is possible that the NADP+-specific enzyme functions to supply NADPH for biosynthetic purposes or to provide NADH via a transhydrogenase reaction (22). In these cases it might be expected that the enzyme would be regulated by the NADPH: NADP+ ratio rather than by the ATP concentration.In view of these results it was decided to study the NADP+-specific enzyme from etiolated pea stems and compare its properties with the properties of the NAD+-specific enzyme from the same source which have already been presented (4-7, 9-11). As with the NAD+-specific enzyme (4) there appears to be a considerable difference between the activation of the enzyme by Mn2+ and Mg2+, the latter only acting as cofactor in the forward direction. In the forward reaction the enzyme has a much lower Km for Mn2+ than Mg2+ and the maximal velocity is also considerably higher. In the reverse reaction, only Mn2+ will activate. Unlike the NAD+-specific enzyme the NADP+-specific enzyme is not greatly affected by the mole fraction of reduced pyridine nucleotide when total pyridine nucleotide (NADP+ + NADPH) is kept constant. It is also much more sensitive to Zn2+ inhibition than the NAD+-specific enzyme when Mg2+ but not Mn2+ is the metal activator. Ca + behaves in a similar manner to Zn2+.The enzyme is inhibited by certain nucleosides and nucleotides; part of the inhibition is due to metal complexing. The enzyme is sensitive to p-chloromercuribenzoate but can be protected by isocitrate in the presence of metal ions or by Mn + alone but not by Mg2+ alone. There is also an apparently concerted inhibition by glyoxylate and oxalacetate.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Nicotinamide Adenine Dinucleotide Phosphate-specific Isocitrate Dehydrogenase from a Higher Plant

Omran

Dennis

1971

Plant Physiol.

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“…typhimurium [24] and Brevibacterium flavum [46] but fructose-l, 6di-phosphate is ineffective as an activator of the acyl-CoA activated enzymes obtained from Thb.…”

Section: Activation By Hexose Phosphatesmentioning

confidence: 99%

Fine control of the conversion of pyruvate (phosphoenolpyruvate) to oxaloacetate in various species

Scrutton

1978

FEBS Letters

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Kinetic, dynamic, and pathway studies of glycerol metabolism byKlebsiella pneumoniae in anaerobic continuous culture: IV. Enzymes and fluxes of pyruvate metabolism

Menzel

Ahrens

Zeng

et al. 1998

Biotechnol. Bioeng.

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The activities of pyruvate kinase (PK), pyruvate: formate‐lyase (PFL), pyruvate dehydrogenase (PDH), and citrate synthase (CS) involved in the anaerobic glycerol conversion by Klebsiella pneumoniae were studied in continuous culture under conditions of steady states and sustained oscillations. Both the in vitro and in vivo activities of PK, PFL, and PDH are strongly affected by the substrate concentration and its uptake rate, as is the in vitro activity of CS. The flux from phosphoenolpyruvate to pyruvate is found to be mainly regulated on a genetic level by the synthesis rate of PK, particularly at low substrate concentration and low growth rate. In contrast, the conversion of pyruvate to acetyl‐CoA is mainly regulated on a metabolic level by the in vivo activities of PFL and PDH. The ratio of in vitro to in vivo activities is in the range of 1 to 1.5 for PK, 5 to 17 for PFL and 5 to 80 for PDH under the experimental conditions. The regulation of in vivo activity and synthesis of these enzymes is sensitive to fluctuations of culture conditions, leading to oscillations of both the in vitro and in vivo activities. In particular, PFL is strongly affected during oscillations; its average in vitro activity is only about half of its corresponding steady‐state value under similar environmental conditions. The average in vitro activities of PDH and PK under oscillations are close to their corresponding steady‐state values. In contrast to all other enzymes measured for the glycerol metabolism by K. pneumoniae PFL and PDH are more effectively in vivo utilized under oscillations than under steady state, underlining the peculiar role of pyruvate metabolism in the dynamic responses of the culture. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 60: 617–626, 1998.

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Regulation of the TCA and Glyoxylate Cycles in Brevibacterium flavum

Cited by 97 publications

References 0 publications

Nicotinamide Adenine Dinucleotide Phosphate-specific Isocitrate Dehydrogenase from a Higher Plant

Nicotinamide Adenine Dinucleotide Phosphate-specific Isocitrate Dehydrogenase from a Higher Plant

Fine control of the conversion of pyruvate (phosphoenolpyruvate) to oxaloacetate in various species

Kinetic, dynamic, and pathway studies of glycerol metabolism byKlebsiella pneumoniae in anaerobic continuous culture: IV. Enzymes and fluxes of pyruvate metabolism

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