BIOC13H3 Lecture Notes - Lecture 18: Electrochemical Gradient, Oligomycin, Sodium-Potassium Alloy
29 Apr 2018
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BIOC13:(Lecture(20( ( Final(
March(28,(2018(
68#
ATP$Synthase!
• ATP(synthase#(sometimes#shortened#to#ATPase),#uses#the#proton#gradient#
created#during#ETN#to#make#ATP#
• It#can#also#break#down#ATP#to#rebuild#the#proton#gradient#
• Belongs#to#the#F(class#of#ATPases#(there’s#actually#many#types#of#ATPases)#
o The#F#class#transports#protons##
• Other#types#include:#
o V-class#that#hydrolyzes#ATP#to#pump#protons#
§ While#F#class#can#also#perform#this#function,#it#usually#doesn’t#
o P-class#uses#ATP#to#allow#ions#in#(eg.#Na/K#ATPase#in#muscles)#
o ABC(class#
Structure'
• Has#a#very#unusual#structure#
and#mechanism##
• There#are#2#parts:#
• F1(is#the#soluble#domain#that#
sticks#out#into#the#matrix,#is#the#
catalytic#domain#for#ATP#
synthesis#
o 5#protein#subunits#
(α3β3γδε)#
o The#γ#is#the#central#stalk#
of#the#ATPase#
• Fo#is#the#membrane#domain#
o Consists#of#abc8-15dF6#and#OSCP#(oligimycin(sensitivity(conferring(
protein)#
o The#number#of#c#units#varies#between#organisms#à#8#in#animals#
o B#and#OSCP#make#up#the#peripheral#stalk#
o Proton#translocating#portion#that#can#create#a#proton#gradient#
• Oligomycin#act#on#the#Fo#domain#to#
inhibit#protein#translocation#
• The#δ#and#ε#subunit#connect#the#F1#and#
Fo#
o Prevents#ATPase#from#
contributing#to#proton#leak#
o ATP#is#always#made#when#
protons#flow#through#Fo#
Document Summary
Atp synthase: atp synthase (sometimes shortened to atpase), uses the proton gradient created during etn to make atp. While f class can also perform this function, it usually doesn"t: p-class uses atp to allow ions in (eg. na/k atpase in muscles, abc class. Fo: prevents atpase from contributing to proton leak, atp is always made when protons flow through fo. Final: the unit doesn"t seem to play a role in atp synthesis but the unit does, the assymetrical unit rotates, changing the confirmation of the unit each time. In open confirmation, the unit is free and waiting for a substrate to bind. In loose confirmation, adp and pi is bound. Evidence in intact atpase: atp synthase modified to express gfp (attached to oscp) when alexa532 (bound to gamma) goes near it. Rotary catalysis: the atpase is also thought of structurally as a rotor and stator section, the rotor rotates during catalysis while the stator doesn"t.
