Gnaiger 1998 Biochim Biophys Acta: Difference between revisions
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{{Publication | {{Publication | ||
|title=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. | |title=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. | ||
|info=[http://www.ncbi.nlm.nih.gov/pubmed/9693739 PMID: 9693739] | |||
|authors=Gnaiger E, Lassnig B, Kuznetsov AV, Margreiter R | |authors=Gnaiger E, Lassnig B, Kuznetsov AV, Margreiter R | ||
|year=1998 | |year=1998 | ||
|journal=Biochim. Biophys. Acta | |journal=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, p<sub>50</sub>, 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. p<sub>50</sub> in the resting state 4 was 0.02 kPa. The apparent kinetic efficiency, Jmax/p<sub>50</sub>, increased from the resting to the active state, despite the decrease of oxygen affinity, 1/p<sub>50</sub>. 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/p<sub>50</sub>. 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]. | |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, p<sub>50</sub>, 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. p<sub>50</sub> in the resting state 4 was 0.02 kPa. The apparent kinetic efficiency, Jmax/p<sub>50</sub>, increased from the resting to the active state, despite the decrease of oxygen affinity, 1/p<sub>50</sub>. 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/p<sub>50</sub>. 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 | |keywords=Oxygen affinity, Catalytic efficiency, Respiratory control, Hypoxia, Mitochondrion, Heart, Liver | ||
| | |mipnetlab=AT_Innsbruck_Gnaiger E | ||
|discipline=Mitochondrial Physiology | |||
}} | }} | ||
{{Labeling | {{Labeling | ||
|instruments=Oxygraph-2k | |instruments=Oxygraph-2k | ||
| | |injuries=Hypoxia | ||
|organism=Rat | |organism=Rat | ||
|tissues=Hepatocyte; Liver | |tissues=Hepatocyte; Liver | ||
|preparations=Isolated Mitochondria, Enzyme | |preparations=Isolated Mitochondria, Enzyme | ||
|kinetics=Oxygen | |kinetics=Oxygen | ||
|topics=Respiration; OXPHOS; ETS Capacity, Flux Control; Additivity; Threshold; Excess Capacity, Coupling; Membrane Potential, Substrate; Glucose; TCA Cycle | |topics=Respiration; OXPHOS; ETS Capacity, Flux Control; Additivity; Threshold; Excess Capacity, Coupling; Membrane Potential, Substrate; Glucose; TCA Cycle | ||
|discipline=Mitochondrial Physiology | |||
}} | }} | ||
Revision as of 15:03, 5 October 2011
» [[Has info::PMID: 9693739]]
Was written by::Gnaiger E, Was written by::Lassnig B, Was written by::Kuznetsov AV, Was written by::Margreiter R (Was published in year::1998) Was published in journal::Biochim. Biophys. Acta
Abstract: [[has 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: has publicationkeywords::Oxygen affinity, has publicationkeywords::Catalytic efficiency, has publicationkeywords::Respiratory control, has publicationkeywords::Hypoxia, has publicationkeywords::Mitochondrion, has publicationkeywords::Heart, has publicationkeywords::Liver
• O2k-Network Lab: Was published by MiPNetLab::AT_Innsbruck_Gnaiger E
Labels:
Stress:Injury and adaptation::Hypoxia Organism: Organism::Rat Tissue;cell: tissue and cell::Hepatocyte; Liver Preparation: Preparation::Isolated Mitochondria, Preparation::Enzyme
Regulation: Topic::Respiration; OXPHOS; ETS Capacity, Topic::Flux Control; Additivity; Threshold; Excess Capacity, Topic::Coupling; Membrane Potential, Topic::Substrate; Glucose; TCA Cycle
HRR: Instrument and method::Oxygraph-2k
