ATP Synthase

Question 1

Name the two sections of ATP synthase and what they contain.

Answer 1

F1 = head & stalk
Fo = membrane

Question 2

How big is 1A?

Answer 2

10^-10M
or
0.1nm

Question 3

Sub-Mitochondrial vesicles

Answer 3

treat the inner mitochondrial membrane with ultrasonic vibrations = ‘inside out’ sub-mitochondiral vesicles

Question 4

How can sub-mitochondiral vesicles be used to determine the structure/function fo ATP synthase?

Answer 4

~ treat the vesicles with low ionic strength media =creates H+ permeable membrane vesicles & F1 particles (ATP synthase activity)
~ add Ca2+ ions to reassemble

Question 5

What can be used to block the proton pumping part of ATP synthase?

Answer 5

Oligomycin or DCCD - blocks Fo

Question 6

How is ATP synthase affected if the respiratory chain is blocked?

Answer 6

it works in reverse and acidifies the middle

Question 7

Which operon codes for E. coli’s F-type ATP synthase?

Answer 7

Unc

Question 8

Fo is composed of __ subunits and each one has a stoichiometry of __.

Answer 8

3:
a - 1
b - 2
c - 10

Question 9

Which subunits are essential for H+ flow?

Answer 9

ALL OF THEM! If 1/10 c subunits are inhibited ALL H+ translocation stops

Question 10

F1 is composed of __ subunits and each one has a stoichiometry of __.

Answer 10

5:
a - 3
b - 3 --> a/b subunits form alternating ring with Y in middle
Y - 1 - is 2 twice alpha helices
d - 1
E - 1

Question 11

What is the role of the proton electrochemical gradient in ATP synthase?

Answer 11

~ not to form ATP

~ to release ATP from the enzyme

Question 12

How many H+ ions are required to turn the ring of c subunits 360 degrees?

Answer 12

10 as 10 c subunits

Question 13

Oxidation of NADH = __ protons = __ ATP

Answer 13

10 protons

3 ATP

Question 14

Oxidation of FADH2 = __ protons = __ ATP

Answer 14

6 protons

2 ATP

Question 15

What is the function of the Y subunit?

Answer 15

~ couples the opening and closing of the nucleotide binding sites
~ changes & coordinates B subunits

Question 16

What evidence is there for the movement of Y subunit?

Answer 16

~ Fluoroescent actin added to Y subunit
~ added His residue to alpha subunits which caused them to bind to Ni-coated base plate
~ images taken at different stages = images of arm going around

Question 17

Open structure of F1 =

Answer 17

empty - ATP binding is poor

Question 18

Tight structure of F1 =

Answer 18

ATP - ATP is formed spontaneously

Question 19

Loose structure of F1 =

Answer 19

ADP + Pi - binding of these molecules is weak