scholarly journals Effect of phenylpyruvate on pyruvate dehydrogenase activity in rat brain mitochondria

1973 ◽  
Vol 134 (2) ◽  
pp. 539-544 ◽  
Author(s):  
John M. Land ◽  
John B. Clark
Keyword(s):  
Rat Brain ◽  
Dehydrogenase Activity ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Competitive Inhibitor ◽  
Brain Mitochondria ◽  
Significant Inhibition ◽  
Complex Activity ◽  
Rat Brain Mitochondria ◽  
Dehydrogenase Complex

1. The effects of phenylpyruvate, a metabolite produced in phenylketonuria, on the pyruvate dehydrogenase-complex activity were investigated in rat brain mitochondria. 2. Pyruvate dehydrogenase activity was measured by two methods, one measuring the release of 14CO2 from [1-14C]pyruvate and the other measuring the acetyl-CoA formed by means of the coupling enzyme, pigeon liver arylamine acetyltransferase (EC 2.3.1.5). In neither case was there significant inhibition of the pyruvate dehydrogenase complex by phenylpyruvate at concentrations below 2mm. 3. However, phenylpyruvate acted as a classical competitive inhibitor of the coupling enzyme arylamine acetyltransferase, with a Ki of 100μm. 4. It was concluded that the inhibition of pyruvate dehydrogenase by phenylpyruvate is unlikely to be a primary enzyme defect in phenylketonuria.

scholarly journals Comparative development of the pyruvate dehydrogenase complex and citrate synthase in rat brain mitochondria

1986 ◽  
Vol 238 (3) ◽  
pp. 729-736 ◽  
Author(s):  
G D A Malloch ◽  
L A Munday ◽  
M S Olson ◽  
J B Clark
Keyword(s):  
Enzyme Activity ◽  
Rat Brain ◽  
Pyruvate Dehydrogenase ◽  
Citrate Synthase ◽  
Post Partum ◽  
Pyruvate Dehydrogenase Complex ◽  
Brain Mitochondria ◽  
Rat Brain Mitochondria ◽  
Developing Rat ◽  
Dehydrogenase Complex

The enzyme activity of the pyruvate dehydrogenase complex (PDHC) was measured in mitochondria prepared from developing rat brain, before and after steady-state dephosphorylation of the E1 alpha subunit. A marked increase in dephosphorylated (fully activated) PDHC activity occurred between days 10 and 15 post partum, which represented approx. 60% of the difference in fully activated PDHC activity measured in foetal and adult rat brain mitochondria. There was no detectable change in the active proportion of the enzyme during mitochondrial preparation nor any qualitative alteration in the detectable catalytic and regulatory components of the complex, which might account for developmental changes in PDHC activity. The PDHC protein content of developing rat brain mitochondria and homogenates was measured by an enzyme-linked immunoadsorbent assay. The development of PDHC protein in both fractions agreed closely with the development of the PDHC activity. The results suggest that the developmental increase in PDHC activity is due to increased synthesis of PDHC protein, which is partly a consequence of an increase in mitochondrial numbers. However, the marked increase in PDHC activity measured between days 10 and 15 post partum is mainly due to an increase in the amount of PDHC per mitochondrion. The development of citrate synthase enzyme activity and protein was measured in rat brain homogenates and mitochondria. As only a small increase in citrate synthase activity and protein was detected in mitochondria between days 10 and 15 post partum, the marked increase in PDHC protein and enzyme activity may represent specific PDHC synthesis. As several indicators of acquired neurological competence become apparent during this period, it is proposed that preferential synthesis of PDHC may be crucial to this process. The results are discussed with respect to the possible roles played by PDHC in changes of respiratory-substrate utilization and the acquisition of neurological competence occurring during the development of the brain of a non-precocial species such as the rat.

Pyruvate Dehydrogenase Activity in Osmotically Shocked Rat Brain Mitochondria: Stimulation by Oxaloacetate

1988 ◽  
Vol 50 (3) ◽  
pp. 673-680 ◽  
Author(s):  
Richard H. Haas ◽  
Geoffrey Thompson ◽  
Bernard Morris ◽  
Kelly Conright ◽  
Torre Andrews
Keyword(s):  
Rat Brain ◽  
Dehydrogenase Activity ◽  
Pyruvate Dehydrogenase ◽  
Brain Mitochondria ◽  
Rat Brain Mitochondria

scholarly journals Evidence for existence of tissue-specific regulation of the mammalian pyruvate dehydrogenase complex

1998 ◽  
Vol 329 (1) ◽  
pp. 191-196 ◽  
Author(s):  
Melissa M. BOWKER-KINLEY ◽  
I. Wilhelmina DAVIS ◽  
Pengfei WU ◽  
A. Robert HARRIS ◽  
M. Kirill POPOV
Keyword(s):  
Tissue Distribution ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Pyruvate Dehydrogenase Kinase ◽  
Synthetic Analogue ◽  
Complex Activity ◽  
Acetyl Coa ◽  
Tissue Specific ◽  
Specific Regulation ◽  
Dehydrogenase Complex

Tissue distribution and kinetic parameters for the four isoenzymes of pyruvate dehydrogenase kinase (PDK1, PDK2, PDK3 and PDK4) identified thus far in mammals were analysed. It appeared that expression of these isoenzymes occurs in a tissue-specific manner. The mRNA for isoenzyme PDK1 was found almost exclusively in rat heart. The mRNA for PDK3 was most abundantly expressed in rat testis. The message for PDK2 was present in all tissues tested but the level was low in spleen and lung. The mRNA for PDK4 was predominantly expressed in skeletal muscle and heart. The specific activities of the isoenzymes varied 25-fold, from 50 nmol/min per mg for PDK2 to 1250 nmol/min per mg for PDK3. Apparent Ki values of the isoenzymes for the synthetic analogue of pyruvate, dichloroacetate, varied 40-fold, from 0.2 mM for PDK2 to 8 mM for PDK3. The isoenzymes were also different with respect to their ability to respond to NADH and NADH plus acetyl-CoA. NADH alone stimulated the activities of PDK1 and PDK2 by 20 and 30% respectively. NADH plus acetyl-CoA activated these isoenzymes nearly 200 and 300%. Under comparable conditions, isoenzyme PDK3 was almost completely unresponsive to NADH, and NADH plus acetyl-CoA caused inhibition rather than activation. Isoenzyme PDK4 was activated almost 2-fold by NADH, but NADH plus acetyl-CoA did not activate above the level seen with NADH alone. These results provide the first evidence that the unique tissue distribution and kinetic characteristics of the isoenzymes of PDK are among the major factors responsible for tissue-specific regulation of the pyruvate dehydrogenase complex activity.

scholarly journals Sirtuin 4 Is a Lipoamidase Regulating Pyruvate Dehydrogenase Complex Activity

Cell ◽  
2014 ◽  
Vol 159 (7) ◽  
pp. 1615-1625 ◽  
Author(s):  
Rommel A. Mathias ◽  
Todd M. Greco ◽  
Adam Oberstein ◽  
Hanna G. Budayeva ◽  
Rumela Chakrabarti ◽  
...  
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Complex Activity ◽  
Dehydrogenase Complex

scholarly journals Platform Engineering of Corynebacterium glutamicum with Reduced Pyruvate Dehydrogenase Complex Activity for Improved Production of l-Lysine, l-Valine, and 2-Ketoisovalerate

2013 ◽  
Vol 79 (18) ◽  
pp. 5566-5575 ◽  
Author(s):  
Jens Buchholz ◽  
Andreas Schwentner ◽  
Britta Brunnenkan ◽  
Christina Gabris ◽  
Simon Grimm ◽  
...  
Keyword(s):  
Corynebacterium Glutamicum ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Fed Batch ◽  
Complex Activity ◽  
Gene Encoding ◽  
Content Type ◽  
Genes Encoding ◽  
Cell Densities ◽  
Dehydrogenase Complex

ABSTRACTExchange of the nativeCorynebacterium glutamicumpromoter of theaceEgene, encoding the E1p subunit of the pyruvate dehydrogenase complex (PDHC), with mutateddapApromoter variants led to a series ofC. glutamicumstrains with gradually reduced growth rates and PDHC activities. Upon overexpression of thel-valine biosynthetic genesilvBNCE, all strains producedl-valine. Among these strains,C. glutamicum aceEA16 (pJC4ilvBNCE) showed the highest biomass and product yields, and thus it was further improved by additional deletion of thepqoandppcgenes, encoding pyruvate:quinone oxidoreductase and phosphoenolpyruvate carboxylase, respectively. In fed-batch fermentations at high cell densities,C. glutamicum aceEA16 Δpqo Δppc(pJC4ilvBNCE) produced up to 738 mM (i.e., 86.5 g/liter)l-valine with an overall yield (YP/S) of 0.36 mol per mol of glucose and a volumetric productivity (QP) of 13.6 mM per h [1.6 g/(liter × h)]. Additional inactivation of the transaminase B gene (ilvE) and overexpression ofilvBNCDinstead ofilvBNCEtransformed thel-valine-producing strain into a 2-ketoisovalerate producer, excreting up to 303 mM (35 g/liter) 2-ketoisovalerate with aYP/Sof 0.24 mol per mol of glucose and aQPof 6.9 mM per h [0.8 g/(liter × h)]. The replacement of theaceEpromoter by thedapA-A16 promoter in the twoC. glutamicuml-lysine producers DM1800 and DM1933 improved the production by 100% and 44%, respectively. These results demonstrate thatC. glutamicumstrains with reduced PDHC activity are an excellent platform for the production of pyruvate-derived products.

scholarly journals The effects of various anions and cations on the regulation of pyruvate dehydrogenase complex activity from pig kidney cortex

1988 ◽  
Vol 253 (3) ◽  
pp. 819-825 ◽  
Author(s):  
T Pawelczyk ◽  
R A Easom ◽  
M S Olson
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Maximal Activity ◽  
Hill Coefficient ◽  
Kidney Cortex ◽  
Complex Activity ◽  
Pig Kidney ◽  
Constant Strength ◽  
Dehydrogenase Complex

The activity of pyruvate dehydrogenase complex (PDC) purified from pig kidney cortex was found to be affected by various uni- and bi-valent ions. At a constant strength of 0.13 M at pH 7.8, K+, Na+, Cl-, HCO3- and HPO4(2-) had significant effects on the activity of PDC: Na+, K+ and HPO4(2-) stimulated, but HCO3- and Cl- inhibited. The stimulatory effect of Na+ was mediated by a change in the Vmax. of PDC only, whereas K+ produced an increase in Vmax. and a change in the Hill coefficient (h). The extent of stimulation produced by HPO4(2-)4 on the activity of PDC was dependent on the concentrations of K+ and Na+. Both cations at concentrations higher than 40 mM partially prevented the effect of HPO4(2-)4. Cl- and HCO3- anions decreased the Vmax. of the enzyme and increased the S0.5 for pyruvate. The effects of Na+, K+, Cl-, HPO4(2-) and HCO3- on the activity of PDC were additive. In the presence of 80 mM-K+, 20 mM-Na+, 10 mM-HPO4(2-), 20 mM-Cl- and 20 mM-HCO3- the activity of PDC was increased by 30%, the S0.5 for pyruvate was increased from 75 to 158 microM and h was decreased from 1.3 to 1.1. Under these conditions and at 1.0 mM-pyruvate, the activity of PDC was 80% of the maximal activity achieved in the presence of these ions and 4.5 mM-pyruvate. The present study suggests that PDC may operate under non-saturating concentrations for substrate in vivo.

scholarly journals Pyruvate Dehydrogenase Activity in Group N Streptococci

1980 ◽  
Vol 33 (1) ◽  
pp. 15 ◽  
Author(s):  
MC Broome ◽  
MP Thomas ◽  
J Hillier ◽  
GR Jago
Keyword(s):  
Dehydrogenase Activity ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Pyruvate Decarboxylase ◽  
Whole Cells ◽  
Streptococcus Lactis ◽  
Dehydrogenase Complex

Pyruvate dehydrogenase activity was detected in whole cells but not in cell-free extracts of Streptococcus lactis. However, the three component enzymes (pyruvate decarboxylase, lipoate acetyltransferase and lipoyl dehydrogenase) of the pyruvate dehydrogenase complex were identified in the cell-free extracts. Whole cells of the three species of group N streptococci formed acetoin and diacetyl only after the pathway forming acetate had become saturated. S. lactis subsp. diacetylactis DRC2 formed more acetoin and diacetyl and less acetate from pyruvate than did S. lactis CW. Strains CIO and DRC2 were able to form acetoin via a-acetolactate or diacetyl and to convert acetoin to butane-2,3-diol. S. cremoris HP was able to form acetoin only via a-acetolactate and could not convert acetoin to butane-2,3cdiol.

scholarly journals A comparison of the regulation of pyruvate dehydrogenase in mitochondria from rat brain and liver

1975 ◽  
Vol 150 (3) ◽  
pp. 397-403 ◽  
Author(s):  
R Jope ◽  
J P Blass
Keyword(s):  
Rat Brain ◽  
Dehydrogenase Activity ◽  
Pyruvate Dehydrogenase ◽  
Active Form ◽  
Energy Charge ◽  
Liver Mitochondria ◽  
Brain Mitochondria ◽  
Ruthenium Red ◽  
Rat Brain And Liver ◽  
Pyruvate Dehydrogenase Phosphatase

The total activity of pyruvate dehydrogenase in mitochondria isolated from rat brain and liver was 53.5 and 14.2nmol/min per mg of protein respectively. Pyruvate dehydrogenase in liver mitochondria incubated for 4 min at 37 degrees C with no additions was 30% in the active form and this activity increased with longer incubations until it was completely in the active form after 20 min. Brain mitochondrial pyruvate dehydrogenase activity was initially high and did not increase with addition of Mg2+ plus Ca2+ or partially purified pyruvate dehydrogenase phosphatase or with longer incubations. The proportion of pyruvate dehydrogenase in the active form in both brain and liver mitochondria changed inversely with changes in mitochondrial energy charge, whereas total pyruvate dehydrogenase did not change. The chelators citrate, isocitrate, EDTA, ethanedioxybis(ethylamine)tetra-acetic acid and Ruthenium Red each lowered pyruvate dehydrogenase activity in brain mitochondria, but only citrate and isocitrate did so in liver mitochondria. These chelators did not affect the energy charge of the mitochondria. Mg2+ plus Ca2+ reversed the pyruvate dehydrogenase inactivation in liver, but not brain, mitochondria. The regulation of the activation-inactivation of pyruvate dehydrogenase in mitochondria from rat brain and liver with respect to energy charge is similar and may be at least partially regulated by this parameter, and the effects of chelators differ in the two types of mitochondria.

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