Electron Microscopy of Multienzyme Complex, especially Pig Heart Pyruvate Dehydrogenase Complex

1970 ◽  
Keyword(s):  
Electron Microscopy ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Multienzyme Complex ◽  
Dehydrogenase Complex

On The Unique Structural Organization of the Saccharomyces Cerevisiae Pyruvate Dehydrogenase Complex

1998 ◽  
Vol 4 (S2) ◽  
pp. 954-955
Author(s):  
James K. Stoops ◽  
Z. Hong Zhou ◽  
John P. Schroeter ◽  
Steven J. Kolodziej ◽  
R. Holland Cheng ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Saccharomyces Cerevisiae ◽  
Pyruvate Dehydrogenase ◽  
Structural Organization ◽  
Pyruvate Dehydrogenase Complex ◽  
The Other ◽  
Oxidative Decarboxylation ◽  
Multienzyme Complex ◽  
The Core ◽  
Dehydrogenase Complex

Dihydrohpoamide acetyl transferase (E2), a catalytic and structural component of a multienzyme complex that catalyzes the oxidative decarboxylation of pyruvate, forms the central core to which the other components are bound. We have utilized protein engineering and 3-D electron microscopy to study the structural organization of the largest multienzyme complex known (Mr ∼ 107). The structures of the truncated 60-mer core (tE2) and complexes of the tE2 associated with a binding protein (BP), and the BP associated with its dihydrohpoamide dehydrogenase (BP'E3) and the intact E2 associated with BP and the pyruvate dehydrogenase (E1) were determined (Figs. 1 and 2). The tE2 core is a pentagonal dodecahedron consisting of 20 cone-shaped trimers interconnected by 30 bridges.Previous studies have given rise to the generally accepted belief that BP and BP'E3 components are bound on the outside of the E2 scaffold and that E1 is similarly bound to the core in variable positions by flexible tethers.

Regulation of pyruvate dehydrogenase complex in ischemic rat heart

1984 ◽  
Vol 246 (6) ◽  
pp. H858-H864 ◽  
Author(s):  
T. B. Patel ◽  
M. S. Olson
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Rat Heart ◽  
Pyruvate Dehydrogenase Complex ◽  
Total Activity ◽  
Control Flow ◽  
Enzyme Complex ◽  
Multienzyme Complex ◽  
Flow Rates ◽  
Perfused Rat Heart ◽  
Dehydrogenase Complex

The effect of flow-induced ischemia on the rate of pyruvate decarboxylation and the activation state of the pyruvate dehydrogenase multienzyme complex was investigated in the isolated, perfused rat heart. Pyruvate dehydrogenase activity in the heart decreased significantly during flow-induced ischemia and was a function of changes in the activation state (i.e., active/total activity) of the enzyme complex. In the absence of pyruvate, the activation state of pyruvate dehydrogenase decreased from nearly 100% active at the normal flow rate (10 ml/min) to 20% active as the flow was reduced to 0.5 ml/min. At high pyruvate levels (5 mM), the activation state increased from nearly 70% active at control flow rates to 100% active during ischemia. At an intermediate pyruvate concentration (0.5 mM), the enzyme complex was maintained at a relatively low activation state (30–35% active) throughout the range of flow rates tested. Ischemia caused elevated perfusate lactate concentrations only when the flow rates were less than 5.0 ml/min. The activation state of the pyruvate dehydrogenase complex in hearts perfused with glucose was also decreased during ischemia.

scholarly journals Lipoylation of the E2 components of the 2-oxo acid dehydrogenase multienzyme complexes of Escherichia coli

1991 ◽  
Vol 277 (1) ◽  
pp. 153-158 ◽  
Author(s):  
L C Packman ◽  
B Green ◽  
R N Perham
Keyword(s):  
Escherichia Coli ◽  
Pyruvate Dehydrogenase ◽  
Catalytic Mechanism ◽  
Chemical Reduction ◽  
Pyruvate Dehydrogenase Complex ◽  
Exchange Chromatography ◽  
Lysine Residue ◽  
Multienzyme Complex ◽  
Dehydrogenase Complex ◽  
Lipoyl Domain

The number of functional lipoyl groups in the dihydrolipoyl acetyltransferase (E2) chain of the pyruvate dehydrogenase multienzyme complex from Escherichia coli has been re-assessed by means of a combination of protein-chemical and mass-spectrometric techniques. (1) After the complex had been treated with N-ethyl[2,3-14C]maleimide in the presence of pyruvate, the lipoyl domains were excised from the complex, treated with NaBH4 and re-exposed to N-ethyl[2,3-14C]maleimide. All the chemically reactive lipoyl groups in the native complex were found to be catalytically active. (2) Proteolytic digests of the separated lipoyl domains were examined for the presence of the lipoylation-site peptide, GDKASME, with and without the lipoyl group in N6-linkage to the lysine residue. Only the lipoylated form of the peptide was detected, suggesting that all three lipoyl domains are fully substituted at this site. (3) The behaviour of each lipoyl domain was examined on ion-exchange chromatography in response to alkylation with 4-vinylpyridine after either chemical reduction of the lipoyl group with dithiothreitol or reductive acetylation by the pyruvate dehydrogenase complex in the presence of pyruvate. All three domains exhibited a quantitative shift in retention time, confirming that each domain was fully substituted by an enzymically reactive lipoyl group. (4) When subjected to electrospray mass spectrometry, each domain gave a mass consistent with a fully lipoylated domain, and no aberrant substitution of the target lysine residue was detected. The same result was obtained for the lipoyl domain from the E. coli 2-oxoglutarate dehydrogenase complex. (5) Previous widespread attempts to assess the number of functional lipoyl groups in the pyruvate dehydrogenase multienzyme complex, which have led to the view that a maximum of two lipoyl groups per E2 chain may be involved in the catalytic mechanism, are in error.

scholarly journals The Pyruvate Dehydrogenase Complex in Sepsis: Metabolic Regulation and Targeted Therapy

2021 ◽  
Vol 8 ◽  
Author(s):  
Zhenhua Zeng ◽  
Qiaobing Huang ◽  
Liangfeng Mao ◽  
Jie Wu ◽  
Sheng An ◽  
...  
Keyword(s):  
Energy Metabolism ◽  
Pyruvate Dehydrogenase ◽  
Metabolic Regulation ◽  
Pyruvate Dehydrogenase Complex ◽  
Aerobic Oxidation ◽  
Tca Cycle ◽  
Protective Effects ◽  
Multienzyme Complex ◽  
Therapeutic Drugs ◽  
Dehydrogenase Complex

Anaerobic glycolysis is the process by which glucose is broken down into pyruvate and lactate and is the primary metabolic pathway in sepsis. The pyruvate dehydrogenase complex (PDHC) is a multienzyme complex that serves as a critical hub in energy metabolism. Under aerobic conditions, pyruvate translocates to mitochondria, where it is oxidized into acetyl-CoA through the activation of PDHC, thereby accelerating aerobic oxidation. Both phosphorylation and acetylation affect PDHC activity and, consequently, the regulation of energy metabolism. The mechanisms underlying the protective effects of PDHC in sepsis involve the regulation on the balance of lactate, the release of inflammatory mediators, the remodeling of tricarboxylic acid (TCA) cycle, as well as on the improvement of lipid and energy metabolism. Therapeutic drugs that target PDHC activation for sepsis treatment include dichloroacetate, thiamine, amrinone, TNF-binding protein, and ciprofloxacin. In this review, we summarize the recent findings regarding the metabolic regulation of PDHC in sepsis and the therapies targeting PDHC for the treatment of this condition.

scholarly journals Dual role of a single multienzyme complex in the oxidative decarboxylation of pyruvate and branched-chain 2-oxo acids in Bacillus subtilis

1983 ◽  
Vol 215 (1) ◽  
pp. 133-140 ◽  
Author(s):  
P N Lowe ◽  
J A Hodgson ◽  
R N Perham
Keyword(s):  
Bacillus Subtilis ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Oxidative Decarboxylation ◽  
Multienzyme Complex ◽  
Complex Activity ◽  
Acid Dehydrogenase ◽  
Branched Chain ◽  
Acid Dehydrogenase Complex ◽  
Dehydrogenase Complex

The pyruvate dehydrogenase and branched-chain 2-oxo acid dehydrogenase activities of Bacillus subtilis were found to co-purify as a single multienzyme complex. Mutants of B. subtilis with defects in the pyruvate decarboxylase (E1) and dihydrolipoamide dehydrogenase (E3) components of the pyruvate dehydrogenase complex were correspondingly affected in branched-chain 2-oxo acid dehydrogenase complex activity. Selective inhibition of the E1 or lipoate acetyltransferase (E2) components in vitro led to parallel losses in pyruvate dehydrogenase and branched-chain 2-oxo acid dehydrogenase complex activity. The pyruvate dehydrogenase and branched-chain 2-oxo acid dehydrogenase complexes of B. subtilis at the very least share many structural components, and are probably one and the same. The E3 component appeared to be identical for the pyruvate dehydrogenase, 2-oxoglutarate dehydrogenase and branched-chain 2-oxo acid dehydrogenase complexes in this organism and to be the product of a single structural gene. Long-chain branched fatty acids are thought to be essential for maintaining membrane fluidity in B. subtilis, and it was observed that the ace (pyruvate dehydrogenase complex) mutant 61142 was unable rapidly to take up acetoacetate, unlike the wild-type, indicative of a defect in membrane permeability. A single pyruvate dehydrogenase and branched-chain 2-oxo acid dehydrogenase complex can be seen as an economical means of supplying two different sets of essential metabolites.

scholarly journals Amino acid sequence around lipoic acid residues in the pyruvate dehydrogenase multienzyme complex of Escherichia coli

1980 ◽  
Vol 187 (3) ◽  
pp. 905-908 ◽  
Author(s):  
G Hale ◽  
R N Perham
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Lipoic Acid ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Amino Acid Sequences ◽  
Single Amino Acid ◽  
Multienzyme Complex ◽  
Dehydrogenase Complex

Amino-acid sequences around two lipoic acid residues in the lipoate acetyltransferase component of the pyruvate dehydrogenase complex of Escherichia coli were investigated. A single amino acid sequence of 13 residues was found. A repeated amino acid sequence in the lipoate acetyltransferase chain might explain this result.

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