Gnaiger 1998 Biochim Biophys Acta
| 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. |
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 respiratory chain and a correspondingly low turnover rate of this enzyme, consistent with the concept of kinetic trapping of oxygen [1]. • Keywords: Oxygen affinity, Catalytic efficiency, Respiratory control, Hypoxia, Mitochondrion, Heart, Liver
• O2k-Network Lab: AT_Innsbruck_GnaigerE
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
