Electron-transfer-pathway state

high-resolution terminology - matching measurements at high-resolution

Electron-transfer-pathway state

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 states.

Reference: Gnaiger_2009_IJBCB; List of respiratory states

Labels:

Enzyme: Complex I, Complex II; Succinate Dehydrogenase"Complex II; Succinate Dehydrogenase" is not in the list (Adenine nucleotide translocase, Complex I, Complex II;succinate dehydrogenase, Complex III, Complex IV;cytochrome c oxidase, Complex V;ATP synthase, Inner mt-membrane transporter, Marker enzyme, Supercomplex, TCA cycle and matrix dehydrogenases, ...) of allowed values for the "Enzyme" property., Complex IV; Cytochrome c Oxidase"Complex IV; Cytochrome c Oxidase" is not in the list (Adenine nucleotide translocase, Complex I, Complex II;succinate dehydrogenase, Complex III, Complex IV;cytochrome c oxidase, Complex V;ATP synthase, Inner mt-membrane transporter, Marker enzyme, Supercomplex, TCA cycle and matrix dehydrogenases, ...) of allowed values for the "Enzyme" property.  Regulation: Respiratory state"Respiratory state" 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. 

Control by substrate type: Pathway control states

• Intact cells: endogenous, exogenous substrate control
• 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.

(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 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)).

(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

• 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'.