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Symptom
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Enzyme
Compound
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Target Concepts:
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Query: EC:6.4.1.1 (
pyruvate carboxylase
)
1,516
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Human blood platelets contain no detectable activity of the enzymes fructose diphosphatase (EC 3.1.3.11), phospho-enolpyruvate carboxykinase (EC 4.1.1.32) and
pyruvate carboxylase
(
EC 6.4.1.1
.). Glucose-6-phosphatase (EC 3.1.3.9) activity is very low. Phosphofructokinase present in human blood platelets, catalyzes a reaction which can be stimulated by AMP in a platelet homogenate, due to the presence of endogenous ADP and
myokinase
. These enzymes are responsible for the formation of fructose-6-phosphate from fructose-1, 6-diphosphate. Pyruvate kinase (EC 2.7.1.40) in human blood platelets belongs to the M-type, which is not inhibited by ATP, at least not under the conditions applied. The results obtained indicate that gluconeogenesis in human blood platelets is not present in the way which has been established for liver and kidney.
...
PMID:Insignificance of gluconeogenesis in human blood platelets. 112 26
1. With freshly isolated blowfly mitochondria 38% of the intramitochondrial adenine nucleotide was present as AMP. 2. On incubation with oxidizable substrates the AMP and ADP concentrations fell and that of ATP rose; with pyruvate together with proline the ATP concentration reached its maximum value at 6min; with glycerol phosphate the phosphorylation of endogenous nucleotide was more rapid. 3. Addition of the uncoupling agent carbonyl cyanide phenylhydrazone caused a rapid fall of ATP and a parallel rise in ADP, then ADP was converted into AMP. 4. This was in contrast with rat liver mitochondria endogenous AMP concentrations, which were always lower than those of blowfly mitochondria and changed little under different metabolic conditions. 5. Evidence is presented that
adenylate kinase
(
EC 2.7.4.3
) has a dual distribution in blowfly mitochondria, a part being located in the matrix space and a part in the space between the outer and inner mitochondrial membranes, as in liver and other mitochondria. 6. The possible regulatory role of changing AMP concentrations in the mitochondrial matrix was investigated. Partially purified
pyruvate carboxylase
(
EC 6.4.1.1
) and citrate synthase (EC 4.1.3.7) were inhibited 30% by 2mm-AMP, whereas pyruvate dehydrogenase (EC 1.2.4.1) was unaffected. 7. AMP activated the NAD(+)-linked isocitrate dehydrogenase (EC 1.1.1.41) activity of blowfly mitochondria in the absence of ADP, but in the presence of ADP, AMP caused inhibition. 8. It is suggested that AMP may exert a controlling effect on the oxidative activity of blowfly mitochondria.
...
PMID:Changes in intramitochondrial adenine nucleotides in blowfly flight-muscle mitochondria. 437 97
Glycerol is a major by-product of the biodiesel industry. In this study we report on the metabolic networks involved in its transformation into pyruvate, phosphoenolpyruvate (PEP) and ATP. When the nutritionally-versatile Pseudomonas fluorescens was exposed to hydrogen peroxide (H2O2) in a mineral medium with glycerol as the sole carbon source, the microbe reconfigured its metabolism to generate adenosine triphosphate (ATP) primarily via substrate-level phosphorylation (SLP). This alternative ATP-producing stratagem resulted in the synthesis of copious amounts of PEP and pyruvate. The production of these metabolites was mediated via the enhanced activities of such enzymes as
pyruvate carboxylase
(PC) and phosphoenolpyruvate carboxylase (PEPC). The high energy PEP was subsequently converted into ATP with the aid of pyruvate phosphate dikinase (PPDK), phosphoenolpyruvate synthase (PEPS) and pyruvate kinase (PK) with the concomitant formation of pyruvate. The participation of the phospho-transfer enzymes like
adenylate kinase
(AK) and acetate kinase (ACK) ensured the efficiency of this O2-independent energy-generating machinery. The increased activity of glycerol dehydrogenase (GDH) in the stressed bacteria provided the necessary precursors to fuel this process. This H2O2-induced anaerobic life-style fortuitously evokes metabolic networks to an effective pathway that can be harnessed into the synthesis of ATP, PEP and pyruvate. The bioconversion of glycerol to pyruvate will offer interesting economic benefit.
...
PMID:Metabolic networks to generate pyruvate, PEP and ATP from glycerol in Pseudomonas fluorescens. 2692 Apr 81
Oxidative stress is known to severely impede aerobic adenosine triphosphate (ATP) synthesis. However, the metabolically-versatile Pseudomonas fluorescens survives this challenge by invoking alternative ATP-generating networks. When grown in a medium with glutamine as the sole organic nutrient in the presence of H
2
O
2
, the microbe utilizes glutamine synthetase (GS) to modulate its energy budget. The activity of this enzyme that mediates the release of energy stored in glutamine was sharply increased in the stressed cells compared to the controls. The enhanced activities of such enzymes as acetate kinase,
adenylate kinase
and nucleotide diphosphate kinase ensured the efficacy of this ATP producing-machine by transferring the high energy phosphate. The elevated amounts of phosphoenol
pyruvate carboxylase
and pyruvate orthophosphate dikinase recorded in the H
2
O
2
exposed cells provided another route to ATP independent of the reduction of O
2
. This is the first demonstration of a metabolic pathway involving GS dedicated to ATP synthesis. The phospho-transfer network that is pivotal to the survival of the microorganism under oxidative stress may reveal therapeutic targets against infectious microbes reliant on glutamine for their proliferation.
...
PMID:The role of glutamine synthetase in energy production and glutamine metabolism during oxidative stress. 2809 38
