Difference between revisions of "Electron-transfer-pathway state"

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Electron-transfer-pathway state

Description

Substrate control states are obtained in mitochondrial preparations (isolated mitochondria, permeabilized cells, permeabilized tissues, tissue homogenate) by depletion of endogenous substrates and addition of specific substrates to the mitochondrial respiration medium. Mitochondrial substrate control states have to be defined complementary to mitochondrial coupling control states.

Substrate control states with electron entry through a single respiratory Complex (electron gaiting);
Physiological substrate control states with convergent electron flow.

Abbreviation: n.a.

Reference: Gnaiger 2009 Int J Biochem Cell Biol

MitoPedia methods: Respirometry

MitoPedia topics: "MitoPedia_Glossary:_Respiratory_states" is not in the list (Enzyme, Medium, Inhibitor, Substrate and metabolite, Uncoupler, Sample preparation, Permeabilization agent, EAGLE, MitoGlobal Organizations, MitoGlobal Centres, ...) of allowed values for the "MitoPedia topic" property. MitoPedia_Glossary:_Respiratory_states"MitoPedia_Glossary:_Respiratory_states" is not in the list (Enzyme, Medium, Inhibitor, Substrate and metabolite, Uncoupler, Sample preparation, Permeabilization agent, EAGLE, MitoGlobal Organizations, MitoGlobal Centres, ...) of allowed values for the "MitoPedia topic" property.

Control by substrate type: Pathway control states

A: Intact cells

Endogenous substrate control: In intact cells, endogenous organic carbon substrates are mobilized in the cytosol as intermediary metabolites transported across the inner mitochondrial membrane and thus exerting control over mitochondrial respiration. If no organic carbon substrates are supplied in the incubation medium, then substrate control is entirely endogenous. Long-term incubation under such conditions leads to progressive states of depletion of endogenous substrates.
Exogenous substrate control: Cells are grown in complex culture media with a variety of organic carbon substrates, and different exogenous substrate control states are achieved by variation of these substrates. Long-term incubation in closed systems without exchange of culture medium leads to progressive states of depletion of exogenous substrates. Incubation of cells in simple media allows for sequential titration of specific carbon substrates (e.g. glucose or fructose; lactate or glutamate) for the study of exogenous substrate control of respiration.

B: Mitochondrial preparations

Specific substrate-inhibitor combinations are selected to establish substrate states for (i) stimulating defined segments of the electron transfer system, or (ii) reconstitution of TCA cycle function.

Substrate control states with electron gaiting: Specific substrate-inhibitor combinations are applied for selectively stimulating electron entry though Complex I, CII, or other branches converging at the Q-junction, particularly with fatty acids and alpha-glycerophosphate (CI respiration, CII respiration, etc.). The most commonly applied substrate states select for Complex I electron input (CI: pyruvate+malate, PM; glutamate+malate, GM), Complex II electron input (CII: succinate+rotenone, S(Rot)), or Complex IV electron input (CIV: ascorbate+TMPD(Ama)).
Physiological substrate control states: Reconstitution of TCA cycle function requires CI+II-linked substrate combinations, such as PMS, GMS, or PMGS, applied simultaneously without inhibitor of any respiratory complexes.

Control by substrate concentration: Kinetic control states

Kinetic substrate or adenylate control: Kinetic studies with variation of a specific substrate (reduced substrate supplying electrons to the ETS; ADP, Pi; O₂; cytochrome c) are analyzed by kinetic functions (e.g. hyperbolic), yielding apparent kinetic constants, such as J_max, K_m', c₅₀, or p₅₀.
Kinetic inhibitor control: Kinetic studies with variation of a specific inhibitor yield apparent kinetic constants, such as the K_I'.

@@ Line 1: / Line 1: @@
 {{MitoPedia
-|description='''Substrate control states''' are defined in mitochondrial preparations (isolated mitochondria, permeabilized cells, permeabilized tissues, tissue homogenate) by depletion of endogenous substrates and addition of defined substrates to the mitochondrial respiration medium. Mitochondrial substrate control states have to be defined complementary to mitochondrial [[coupling control state]]s.
+|abbr=n.a.
-|info=[[Gnaiger_2009_IJBCB]]
+|description='''Substrate control states''' are obtained in [[mitochondrial preparations]] (isolated mitochondria, permeabilized cells, permeabilized tissues, tissue homogenate) by depletion of endogenous substrates and addition of specific substrates to the mitochondrial respiration medium. Mitochondrial substrate control states have to be defined complementary to mitochondrial [[coupling control state]]s.
+# [[Respiratory Complex-specific substrate control state|Substrate control states with electron entry through a single respiratory Complex]] (electron gaiting);
+# [[Physiological substrate control state]]s with convergent electron flow.
+|info=[[Gnaiger 2009 Int J Biochem Cell Biol]]
+}}
+{{MitoPedia methods
+|mitopedia method=Respirometry
 }}
 {{MitoPedia topics
-|mitopedia topic=Respiratory state
+|mitopedia topic=MitoPedia_Glossary:_Respiratory_states
 }}
-==Control by substrate type: Pathway control states==
+== Control by substrate type: Pathway control states ==
+'''A: Intact cells'''
+# '''Endogenous substrate control:''' In intact cells, endogenous organic carbon substrates are mobilized in the cytosol as intermediary metabolites transported across the inner mitochondrial membrane and thus exerting control over mitochondrial respiration. If no organic carbon substrates are supplied in the incubation medium, then substrate control is entirely endogenous. Long-term incubation under such conditions leads to progressive states of depletion of endogenous substrates.
+# '''Exogenous substrate control:''' Cells are grown in complex culture media with a variety of organic carbon substrates, and different exogenous substrate control states are achieved by variation of these substrates. Long-term incubation in closed systems without exchange of culture medium leads to progressive states of depletion of exogenous substrates. Incubation of cells in simple media allows for sequential titration of specific carbon substrates (e.g. glucose or fructose; lactate or glutamate) for the study of exogenous substrate control of respiration.
-*Intact cells: [[endogenous]], [[exogenous]] substrate control
+'''B: [[Mitochondrial preparations]]'''
-*Mitochondrial preparations
+: Specific substrate-inhibitor combinations are selected to establish substrate states for (i) stimulating defined segments of the electron transfer system, or (ii) reconstitution of [[TCA cycle]] function.
-Specific substrate-inhibitor combinations are selected to establish substrate states for (i) stimulating defined segments of the electron transfer system, or (ii) reconstitution of [[TCA cycle]] function.
-(i) Specific substrate-inhibitor combinations are applied for selectively stimulating electron entry though Complex I, CII, or other branches converging at the [[Q-junction]], particularly with [[fatty acid]]s and alpha-[[glycerophosphate]] (CI respiration, CII respiration, etc.). The most commonly applied substrate states select for [[Complex I]] electron input (CI: pyruvate+malate, PM; glutamate+malate, GM), [[Complex II]] electron input (CII: succinate+rotenone, S(Rot)), or [[Complex IV]] electron input (CIV: ascorbate+TMPD(Ama)).
+# '''Substrate control states with electron gaiting:''' Specific substrate-inhibitor combinations are applied for selectively stimulating electron entry though Complex I, CII, or other branches converging at the [[Q-junction]], particularly with [[fatty acid]]s and alpha-[[glycerophosphate]] (CI respiration, CII respiration, etc.). The most commonly applied substrate states select for [[Complex I]] electron input (CI: pyruvate+malate, PM; glutamate+malate, GM), [[Complex II]] electron input (CII: succinate+rotenone, S(Rot)), or [[Complex IV]] electron input (CIV: ascorbate+TMPD(Ama)).
+# '''Physiological substrate control states:''' Reconstitution of TCA cycle function requires CI+II-linked substrate combinations, such as PMS, GMS, or PMGS, applied simultaneously without inhibitor of any respiratory complexes.
-(ii) Reconstitution of TCA cycle function requires a CI+II-related substrate combination, such as PMS, GMS, or PMGS, applied simultaneously without inhibitor of any respiratory complexes.
-==Control by substrate concentration: Kinetic control states==
+== Control by substrate concentration: Kinetic control states ==
-*Kinetic substrate or adenylate control: Kinetic studies with variation of a specific substrate (reduced substrate supplying electrons to the ETS; ADP, Pi; O<sub>2</sub>; cytochrome ''c'') are analyzed by kinetic functions (e.g. hyperbolic), yielding apparent kinetic constants, such as ''J''<sub>max</sub>, ''K''<sub>m</sub>', ''c''<sub>50</sub>, or ''p''<sub>50</sub>.
-*Kinetic inhibitor control: Kinetic studies with variation of a specific inhibitor yield apparent kinetic constants, such as the ''K''<sub>I</sub>'.
+# '''Kinetic substrate or adenylate control''': Kinetic studies with variation of a specific substrate (reduced substrate supplying electrons to the ETS; ADP, Pi; O<sub>2</sub>; cytochrome ''c'') are analyzed by kinetic functions (e.g. hyperbolic), yielding apparent kinetic constants, such as ''J''<sub>max</sub>, ''K''<sub>m</sub>', ''c''<sub>50</sub>, or ''p''<sub>50</sub>.
+# '''Kinetic inhibitor control''': Kinetic studies with variation of a specific inhibitor yield apparent kinetic constants, such as the ''K''<sub>I</sub>'.