Oxidative Phosphorylation via ATP Synthase

Six vocabulary flashcards covering the structure, components, and energy-coupling concepts of ATP synthase in oxidative phosphorylation.

ATP Synthase components

3 alpha-beta subunits; gamma central stalk; b subunits (stator); delta subunit that connects stator to alpha; 8-17 c subunits; a subunit bound to c subunits

F1 Component

Catalyzes ATP synthesis by a binding change mechanism

F0 Component

The membrane-embedded portion of ATP synthase containing a c-ring, whose rotation is driven by the dissipation of the proton gradient and drives conformational change in the F1 component

c-Ring Rotation

Neg charged Glut (or Asp) on each C subunit grabs an H+, creating glutamic acid/ aspartic acid, which is more hydrophobic, so it moves away from the a subunit towards the IMM, causing the entire c rotor to rotate; this rotation causes an H+ to be able to exit and another proton to enter the rotor

Binding Change Mechanism

rotation of the γ stalk forces the three β subunits of F1 to cycle through Loose (L) (takes up ADP + Pi), Tight (T) (phosphorylates ADP to ATP), and Open (O) (releases ATP) states, synthesizing one ATP per cycle.

pH vs [H+] and coupling of e- transport and ATP synthesis

Ions can’t move freely across IMM to prevent gradient disruption; at low pH, [H+] is high (IMS)

reduction-oxidation (redox) reactions

involve the transfer of e-s from one atom/ molecule to another

oxidation

loss of electrons; causes an increase in oxidation state

reduction

gain of electrons; causes a decrease in oxidation state

oxidation state calculation

1. each bond between C and H = decrease by 1

2. each bond between C and a more electroneg. element = increase by 1

cellular respiration

in the matrix, food molecules are oxidized into ATP, NADH, and FADH2; in the IMS, movement of e-s and H+ gradient is formed via the ETC; then ATP synthesis

oxidized vs reduced molecules

oxidized (e- accepting) = NAD+, FAD; reduced (e- donors/ carriers) = NADH, FADH2

Electron Transport System

Contains 4 complexes: e-s enter at 1 (NADH → NAD) and 2 (FADH2 → FAD); e-s are shuttled via CoQ (from 1 and 2 to 3) and Cyt c (from 3 to 4); then e-s transferred to terminal e- acceptor (O2), which is reduced to H2O; each successive complex has a higher e- affinity than the previous

oxidative phosphorylation

H+s in IMS → matrix via ATPase; harnesses (via ETS and H+ gradient) energy released by oxidation of organic molecules to drive ADP → ATP

ADP control of ATPase

F1 is unable to change without ADP binding, so H+ no longer passes and F0 rotor stops moving. This causes H+ in IMS to build up at first; eventually, e= transport stops, causing increases in [NADH] and [FADH2], so [NAD+] and [FAD] decreases; CAC then slows, causing food metabolism to slow

DNP

protonophore that pokes holes in the IMM, allowing H+ to flow freely, dissipating the H+ gradient; ETC will continue d/t the lack of H+ build-up, but energy is lost as heat, uncoupling oxidative phosphorylation from ATP synthesis.