21. ATP synthase Flashcards
what is the goal of ATP synthase
produce ATP from ADP and Pi using the H+ gradient established from the ETC
describe the relationship between ATP synthesis and O2 consumption
they’re coupled; ie neither happens without the other
what happens if you take antibiotics that directly block ATP synthase
O2 consumption is also blocked, since the two are coupled
describe the role of DNP
DNP is a weak acid that uncoupled ATP synthesis and O2 consumption. It carries protons across the bilayer to dissipate the gradient without producing ATP
describe the two structural components of ATP synthase
Fo channel and the F1 sphere
how are the Fo channel and the F1 sphere connected
through the gamma stalk, which runs through the center of the F1 sphere
describe the structure of the Fo channel and each component of it
has a, b, and c (10-14) subunits.
a= half entry/exit channels
b= peripheral stalk
c=rotating part
describe the structure of the F1 sphere and each component of it
alpha, beta, and gamma subunuts.
a and b: orange slice shaped, make up the sphere
y=central rotating stalk that goes through a/b subunits
describe the Kd values of ATP synthase for ATP and ADP
Kd ATP = low (high affinity)
Kd ADP = high (low affinity)
what does the reaction coordinate diagram look like for ATP synthase
the release of ATP from the enzyme has the biggest barrier due to the high ATP affinity
since ATP synthase has such a high ATP affinity, how is it released
there is a conformational change that binds ATP less tightly so that it can be released
what components of ATP synthase rotate
c subunit of Fo channel and the gamma stalk of F1 sphere
describe the rotation of the gamma stalk/c subunit
c subunit rotates, causing the stalk to rotate, and it will move relative to the spherical immobile head and come in contact with a new beta subunit each turn
what causes the c subunits to rotate (be detailed)
each c has an Asp midway across the membrane. A proton enters through a and binds there, causing Asp to no longer be negatively charged
a pos charged Arg from the a sub was interacting with the neg Asp, but now that Asp isn’t neg Arg swings and displaces the Asp-bound proton, putting it over the exit tunnel. proton leaves through the a exit tunnel and into the matrix.
C rotates, causing the Asp-Arg interaction goes back to normal
what are the three conformations of the beta subunit
open, loose, tight
