ATP biosynthesis Flashcards
what evidence supports the existence of the chemiosmotic gradient
oxphos requires an intact IMM
IMM is impermeable to ions
electron transport creates a measurable electrochemical gradient across IMM
compounds that increase the permeability of the IMM allow electron transport but inhibit ATP synthesis
what drives protons back into the matrix providing the energy for ATP synthesis
proton-motive force created by the electrochemical gradient
what is the pH of the IMS and the matrix
IMS: 7
matrix: 8
what conditions does mitochondrial ATP synthase play a key role in
cancer, obesity, neuropathies, Alzheimer’s and Parkinson’s, microbial infections, mitochondrial disease, immune defiency, cycstic fibrosis, diabetes and hypothyroidism
which region of ATPase is intramembrane
C-ring domain
what does the rotation of ATP synthase cause
the formation of ATP by bringing ADP and a phosphate closer together
what types of energy are converted into one another in oxphos
electrochemical energy in the gradient
mechanical energy in the rotation of enzyme
chemical energy in the formation of ATP
what method is primarily used to study ATP synthase function
structural method using cryo-EM to make a 3D model
what is the F0 and F1 domain of ATP synthase
where are they
F0: intramembrane C domain structure forms a channel that allows flow of protons
F1: motor domain that protrudes into the matrix - rotation of central stalk causes conformational change of the 3 active sites
what is the stator of ATP synthase
what is its role
structural support
prevention of unwanted rotation
transmembrane spanning
integration with the membrane
where is the substrate channel of ATP synthase
ADP and Pi
what is the importance of substrate channelling of ATP synthase
channelling substrates directly to the active sites:
optimized ATP synthesis, prevents wasteful hydrolysis of ATP, control of reaction pathway
how many C subunits make up the C ring of the F0 region in human ATP synthase
8
which regions of ATP synthase rotate
intramembrane C ring and central rod
where is the DP site of ADP binding in ATP synthase
between subunit alpha (chain C) and beta (chain D)
describe the F1 region of ATP synthase
3 alpha and 3 beta alternating domains around the central rotating gamma domain
where is ATP synthase located in eukaryotes and in prokaryotes
EU: IMM
PRO: plasma membrane
what is the pKa of glutamate residues
4.25
how was the substrate binding sites of ATP synthase identified
structural studies
where is the active site of ATP synthase
between the alpha and beta subunits (chain C and D)
how was the function of ATP synthase determined using structural studies
a series of conformational changes can be identified from structural information which tell us how the enzyme functions
Rotary catalysis of ATP generation characterised by structural information
why does the C-ring only rotate in one direction during ATP synthesis
unidirectional rotation is crucial for ATP synthesis
if it went the other way it would hydrolyse ATP
structure and mechanical constraints
which residue acts as a proton transporter across the IMM
glutamate
what causes deprotonation and deprotonation
Deprotonation occurs when the environment is at a higher pH than the pKa of the residue
protonation occurs when the environment is at a lower pH than the pKa of the residue
