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Gnaiger 1998 Biochim Biophys Acta

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Gnaiger E, Lassnig B, Kuznetsov AV, Margreiter R (1998) Mitochondrial respiration in the low oxygen environment of the cell: Effect of ADP on oxygen kinetics. Biochim Biophys Acta 1365: 249-254.

Β» PMID: 9693739

Gnaiger E, Lassnig B, Kuznetsov AV, Margreiter R (1998) Biochim Biophys Acta

Abstract: Oxygen levels in the intracellular microenvironment of tissues such as heart are extremely low, at 1–2% of standard atmospheric oxygen pressure. Kinetic studies with isolated mitochondria suggest a regulatory role of oxygen under these conditions, particularly in active states at high ADP concentration, when oxygen affinity was lower than in the resting state at ADP limitation. The oxygen pressure at 50% of maximum flux, p50, was 0.035 and 0.057 kPa in heart and liver mitochondria, respiring in State 3 on substrates for Complex I or II and II, respectively. p50 in the resting State 4 was 0.02 kPa. The apparent kinetic efficiency, Jmax/p50, increased from the resting to the active state, despite the decrease of oxygen affinity, 1/p50. Consequently, the relative increase of respiratory flux by ADP activation, expressed as the adenylate control ratio, declined under hypoxia, but not to the extreme of a complete loss of the scope for activation, which would occur at constant Jmax/p50. High oxygen affinity is achieved by an excess capacity of cytochrome c oxidase relative to the electron transfer system and a correspondingly low turnover rate of this enzyme, consistent with the concept of kinetic trapping of oxygen [1]. β€’ Keywords: Oxygen affinity, Catalytic efficiency, Respiratory control, Hypoxia, Mitochondrion, Heart, Liver

β€’ O2k-Network Lab: AT_Innsbruck_Gnaiger E


Labels:

Stress:Hypoxia  Organism: Rat  Tissue;cell: Hepatocyte; Liver"Hepatocyte; Liver" is not in the list (Heart, Skeletal muscle, Nervous system, Liver, Kidney, Lung;gill, Islet cell;pancreas;thymus, Endothelial;epithelial;mesothelial cell, Blood cells, Fat, ...) of allowed values for the "Tissue and cell" property.  Preparation: Isolated Mitochondria"Isolated Mitochondria" is not in the list (Intact organism, Intact organ, Permeabilized cells, Permeabilized tissue, Homogenate, Isolated mitochondria, SMP, Chloroplasts, Enzyme, Oxidase;biochemical oxidation, ...) of allowed values for the "Preparation" property., Enzyme 

Regulation: Respiration; OXPHOS; ETS Capacity"Respiration; OXPHOS; ETS Capacity" is not in the list (Aerobic glycolysis, ADP, ATP, ATP production, AMP, Calcium, Coupling efficiency;uncoupling, Cyt c, Flux control, Inhibitor, ...) of allowed values for the "Respiration and regulation" property., Flux Control; Additivity; Threshold; Excess Capacity"Flux Control; Additivity; Threshold; Excess Capacity" is not in the list (Aerobic glycolysis, ADP, ATP, ATP production, AMP, Calcium, Coupling efficiency;uncoupling, Cyt c, Flux control, Inhibitor, ...) of allowed values for the "Respiration and regulation" property., Coupling; Membrane Potential"Coupling; Membrane Potential" is not in the list (Aerobic glycolysis, ADP, ATP, ATP production, AMP, Calcium, Coupling efficiency;uncoupling, Cyt c, Flux control, Inhibitor, ...) of allowed values for the "Respiration and regulation" property., Substrate; Glucose; TCA Cycle"Substrate; Glucose; TCA Cycle" is not in the list (Aerobic glycolysis, ADP, ATP, ATP production, AMP, Calcium, Coupling efficiency;uncoupling, Cyt c, Flux control, Inhibitor, ...) of allowed values for the "Respiration and regulation" property. 


HRR: Oxygraph-2k 


Terminology

  • State 2 in this publication (different from definitions by Chance, Williams 1955) has the meaning of a LEAK state of respiration, without added adenylates (no ADP and no ATP) in the presence of defined respiratory carbon substrates.
  • State 4 in this publication is a LEAK state of respiration induced by addition of defined respiratory carbon substrates and a high concenteration of ATP.
  • State 3 in this publication is measred at high [ADP] close to saturated [ADP] (OXPHOS capacity) in the presence of added ATP.