Respiratory Complexes and ATP Synthesis

Flashcards covering respiratory complexes, electron transport chain carriers, complex-specific inhibitors, ATP synthase mechanisms, and mitochondrial uncoupling.

Flavoproteins

Polypeptides bound to either FAD or FMN that serve as electron carriers.

Cytochromes

Electron carriers that contain heme groups bearing Fe or Cu metal ions.

Ubiquinone (coenzyme Q)

A lipid-soluble molecule made of five-carbon isoprenoid units.

Iron-sulfur proteins

Electron carriers that contain Fe in association with inorganic sulfur, arranged in order of increasingly positive redox potential.

Complex I

Also known as NADH-CoQ Oxidoreductase; it involves the translocation of $H^+$ and is inhibited by rotenone, amytal, piericidin A, rolliniastatin-1, and meperidine.

Complex II

Also known as Succinate-CoQ Oxidoreductase; it is inhibited by carboxin, boscalid, fluopyram, sedaxene, and bixafen.

Complex III

Also known as CoQ-cyt c Oxidoreductase; its inhibitors include antimycin, myxothiazole, stigmatellin, and azoxystrobin.

Complex IV

Also known as Cyt C Oxidase; it is inhibited by CO (competitive), $CN^-$ and $H_2S$ (noncompetitive), and $HCOOH$ or $HN=N^+=N^-$ (uncompetitive).

Binding-change mechanism

The mechanism of ATP Synthase driven by conformational changes to facilitate the synthesis of ATP.

Chemiosmotic Coupling

A model of oxidative phosphorylation where the proton gradient resulting from the electron transport chain (ETC) drives the synthesis of ATP.

Mitochondrial Uncoupling

The discharge of the electrochemical gradient through the transport of $H^+$ across the inner membrane to the matrix, which effectively turns off ATP synthesis.

2,4-dinitrophenol

A lipophilic weak acid that acts as a mitochondrial uncoupler by entering the matrix and dissociating.

Brown Fat

Tissue with high mitochondrial and cytochrome content that generates heat via non-shivering thermogenesis.

Thermogenin

An uncoupling protein found exclusively in brown fat that regulates the uncoupling of oxidative phosphorylation to produce heat.

Citric Acid Cycle Yield

The production of 3 NADH and 1 FADH2 from each molecule of acetyl CoA that enters the cycle.

Respiratory control

The regulation of catabolism based on the ratio of $NAD^+/FAD$ to $NADH/FADH_2$; for instance, exercise increases the $NAD^+/FAD$ ratio to turn catabolism on.