Biochemistry Ch. 21- Proton Motive Force

Proton Motive Force

unequal charge across the membrane

Chemical gradient in mitochondria

pH outside is more acidic than inside

Charge gradient in mitochondria

membrane potential is 0.14 V

F0 Unit

found in the membrane and is a proton conducting unit

subunit a

two half channels that protons enter

subunit c ring

proteins bind to a central glutamic acid, causes rotation

F1 unit

a catalytic unit with ATPase activity

gamma subunit

rotational stalk that causes change in alpha/beta subunits

epsilon subunits

stabilizes the stalk, reduces torque

beta subunit

stabilizes the central stalk, attaches F0 to F1

delta subunit

connects stalk to F1 head

alpha/beta dimers

different conformations for synthesis of ATP

Open form

nucleotides can bind or be released from beta subunit

Loose form

nucleotides are trapped

Tight

ATP is made from ADP and Pi

Reality: amount of ATP made from one NADH

2.5

Theoretical: amount of ATP made from one NADH

3.3

Reality: amount of ATP made from one FADH2

1.5 

Theoretical: amount of ATP made from one FADH2

2

How much ATP do you get from using a glycerol 3-phosphate shuttle?

theoretical: 36 ATP, actual: 30 ATP

How much ATP do you get from using a malate-aspartate shuttle?

theoretical: 38ATP, actual: 32ATP

ATP-ADP translocase

entry of ADP is coupled to ATP exit

Nonshivering thermogenesis

brown fat cells, have a UCP-1 shuttle that turns the energy into heat