Ch. 21: Proton Motive Force

the chemiosmotic theory

electron transport and ATP synthesis are coupled by a proton gradient across the inner mitochondrial membrane

proton-motive force

the chemical gradient and charge gradient generated by the oxidation of NADH and FADH2

ATP synthase (complex V)

consists of a proton conducting (F0/stalk) unit and an ATP-synthesizing (F1/knob) unit

F0 unit

“stalk”, proton channel proton-conducting transmembrane unit

F1 unit

“knob”, catalytic subunits inside the mitochondrial matrix, ATP synthesizing unit

electrostatics (neutralization of Asp/Glu by H+) and Le Chatelier’s Principle (from high to low concentration)

what 2 factors drive rotation of the c ring

rotation of c ring

what drives rotation of y-subunit

the open site

what site is ATP released from in y subunit

intermembrane half-channel and matrix half-channel

what are the 2 units of subunit a?

subunit c

hydrophobic ring structure formed, embedded in innermitochondrial membrane, and has Glutamate or Aspartate (-)

ATP-ADP translocase

antiporter that mediates coupled transportation ATP out and ADP in to matrix

phosphate transporter

symporter that facilitates both 1 H+ and 1 Pi simultaneously

how many H+ are needed from 1 ATP production

4 

glycerol 3-phosphate shuttle

how NADH from glycolysis enters the mitochondrial matrix

molecules of ADP phosphorylated/atoms of O2 reduced

P:O Ratio

2 pyruvate, 2 ATP, and 2 NADH

products of glycolysis

1 NADH

products of PDH complex

products of TCA cycle

3 NADH, FADH2, and ATP

regulation of ATP synthase

level of ADP

respiratory/acceptor control

term for the regulation of ATP synthase by O2 consumption and electron flow through ETC

non-shivering thermogenesis

occurs in the brown fat of rodents and is the uncoupling of ETC from ATP synthase which generates heat

uncoupling protein 1 (UCP-1)/thermogenin

an integral membrane protein on the inner mitochondrial membrane that is permeable to protons

mitochondrial matrix

the pH is higher in which part of the mitochondria

steps of ATP synthesis by ATP synthase

1. ADP and Pi bind to the L site

2. the B subunit converts from the L to the T conformation; ATP is synthesized from ADP and Pi

3. the B subunit is converted from the T to the O conformation; ATP is released

out of the mitochondrial matrix

what direction is ATP^4- transported during times of active oxidative phosporylation?

the electrochemical gradient (membrane potential)

what drives the transport of adenine nucleotides?

high ADP concentration, and high oxygen concentration

what factors increase ETC activity

low NADH concentration, low phosphate concentration, and large difference in H+ across the inner mitochondrial membrane

what factors decrease ETC activity