Difference between revisions of "State 2"

Latest revision as of 18:45, 1 January 2021

high-resolution terminology - matching measurements at high-resolution

State 2

Description

Substrate limited state of residual oxygen consumption, after addition of ADP to isolated mitochondria suspended in mitochondrial respiration medium in the absence of reduced substrates (ROX_D). Residual endogenous substrates are oxidized during a transient stimulation of oxygen flux by ADP. The peak – supported by endogenous substrates – is, therefore, a pre-steady state phenomenon preceding State 2. Subsequently oxygen flux declines to a low level (or zero) at the steady State 2 (Chance and Williams 1955). ADP concentration (D) remains high during ROX_D.

Abbreviation: ROX_D

Reference: Chance 1955 JBC-III, Gnaiger 2020 BEC MitoPathways

MitoPedia concepts: Respiratory state, Find

MitoPedia topics: EAGLE

Communicated by Gnaiger E 2010-12-20, edited 2016-02-21.

ROX versus LEAK: towards a concept-linked terminology of respiratory states

ROX

State 2 is equivalent to residual oxygen consumption, ROX. We have sought independent controls on whether State 2 corresponds to complete oxidation of the system. It is logical that this be so, for respiration is zero in State 2 because substrate, not phosphate acceptor, is limiting (Chance and Williams 1955).

Clarification

A numerical sequence of terms defining respiratory states has been introduced by Chance and Williams. The State 2 and 4 terminology, however, has become confusing and misunderstood: ‘.. the controlled respiration prior to addition of ADP, which is strictly termed “state 2”, is functionally the same as state 4, and the latter term is usually used for both states’ (Nicholls and Ferguson 1992). Alchemy has a tradition of using the same term for multiple meanings and different terms for the same. A termonological extension from integers to the fraction 3½ has been suggested to indicate an intermediate mitochondrial energy state somewhere between States 3 and 4. Paradoxically, a fractional numbering system (real numbers of mathematics) would suggest that ADP-activated hypoxia were intermediate between States 3.0 and 5.0, i.e. State 4.0. This state of terminology requires fundamental reconsideration for clarification, particularly for extending bioenergetics to mitochondrial respiratory physiology and OXPHOS analysis.

More details

» LEAK respiration

» MitoPedia: Respiratory states

@@ Line 1: / Line 1: @@
 {{MitoPedia
 |abbr=ROX<sub>D</sub>
-|description=Substrate limited state of [[residual oxygen consumption]], after addition of ADP to isolated mitochondria suspended in mitochondrial respiration medium in the absence of reduced substrates (ROX<sub>D</sub>).  Residual endogenous substrates are oxidized during a transient stimulation of oxygen flux by ADP. Subsequently oxygen flux declines to a low level (or zero) at the steady '''State 2''' ([[Chance_1955_JBC-III|Chance and Williams 1955]]). ADP concentration (D) remains high during ROX<sub>D</sub>.
+|description=[[File:ROX.jpg |link=Residual oxygen consumption]] Substrate limited state of [[residual oxygen consumption]], after addition of [[ADP]] to isolated mitochondria suspended in mitochondrial respiration medium in the absence of reduced substrates (ROX<sub>D</sub>).  Residual endogenous substrates are oxidized during a transient stimulation of oxygen flux by ADP. The peak – supported by endogenous substrates – is, therefore, a pre-steady state phenomenon preceding State 2. Subsequently oxygen flux declines to a low level (or zero) at the steady '''State 2''' ([[Chance_1955_JBC-III|Chance and Williams 1955]]). ADP concentration (D) remains high during ROX<sub>D</sub>.
-|info=[[MiPNet12.15]], [[Chance 1955 JBC-III]]
+|info=[[Chance 1955 JBC-III]], [[Gnaiger 2020 BEC MitoPathways]]
-|type=Respiration
 }}
-{{Labeling
+{{MitoPedia concepts
-|discipline=Mitochondrial Physiology
+|mitopedia concept=Respiratory state, Find
-|preparations=Isolated Mitochondria, Permeabilized Cell or Tissue; Homogenate
-|kinetics=ADP; Pi, Reduced Substrate; Cytochrome c
-|topics=Respiratory state, Respiration; OXPHOS; ETS Capacity
-|type=Respiration
 }}
-==An alternative protocol==
+{{MitoPedia topics
+|mitopedia topic=EAGLE
-In contrast to the definition of State 2 by Chance and Williams (1955, 1956), a respiratory [[LEAK]] state may be induced as the second respiratory state in a protocol with isolated mitochondria, permeabilized tissues, or permeabilized cells, adding the mitochondrial preparation to respiration medium containing inorganic phosphate ([[State 1]]), then adding reduced substrate (no external adenylates). This second state (Estabrook 1967) is a non-phosphorylating LEAK state, ''L''<sub>N</sub> (N for no adenylates; Gnaiger 2009), when substrate-saturated respiration compensates for the proton leak (mainly) in the absence of ADP. State 2 (Chance and Williams 1955), however, is defined as high [ADP] without external substrates, followed by [[State 3]] induced by addition of reduced substrate(s).
+}}
+ Communicated by [[Gnaiger E]] 2010-12-20, edited 2016-02-21.
-==References==
+== ROX versus LEAK: towards a concept-linked terminology of respiratory states ==
-Chance B, Williams GR (1955) Respiratory enzymes in oxidative phosphorylation. III. The steady state. J. Biol. Chem. 217: 409-427.
-Chance B, Williams GR (1956) The respiratory chain and oxidative phosphorylation. Adv. Enzymol. 17: 65-134.
+::: '''ROX'''
+:::: State 2 is equivalent to residual oxygen consumption, ROX.  ''We have sought independent controls on whether State 2 corresponds to complete oxidation of the system. It is logical that this be so, for respiration is zero in State 2 because substrate, not phosphate acceptor, is limiting'' ([[Chance_1955_JBC-III|Chance and Williams 1955]]).
-Estabrook R (1967) Mitochondrial respiratory control and the polarographic measurement of ADP:O ratios. Methods Enzymol. 10: 41-47.
+::: '''Clarification'''
+:::: A numerical sequence of terms defining respiratory states has been introduced by Chance and Williams. The State 2 and 4 terminology, however, has become confusing and misunderstood:  ‘.. the controlled respiration prior to addition of ADP, which is strictly termed “state 2”, is functionally the same as state 4, and the latter term is usually used for both states’ (Nicholls and Ferguson 1992). Alchemy has a tradition of using the same term for multiple meanings and different terms for the same.  A termonological extension from integers to the fraction 3½ has been suggested to indicate an intermediate mitochondrial energy state somewhere between States 3 and 4. Paradoxically, a fractional numbering system (real numbers of mathematics) would suggest that ADP-activated hypoxia were intermediate between States 3.0 and 5.0, i.e. State 4.0. This state of terminology requires fundamental reconsideration for clarification, particularly for extending bioenergetics to mitochondrial respiratory physiology and OXPHOS analysis.
-Gnaiger E (2009) Capacity of oxidative phosphorylation in human skeletal muscle. New perspectives of mitochondrial physiology. Int. J. Biochem. Cell Biol. 41: 1837–1845. PMID: 19467914
+::: '''More details'''
+::::» [[LEAK respiration]]
+::::» [[MitoPedia: Respiratory states]]