BIOC13H3 Lecture Notes - Lecture 14: Electrochemical Gradient, Nigericin, Valinomycin
29 Apr 2018
School
Department
Course
Professor
!"#$%&'()*+,-.*(%/( ( 01234(
53.+6(%78(9:%;(
52#
Electrochemical,Gradient,and,Uncoupled,
Respiration!
Proton&Electrochemical&
Gradient&
Effect&of&Ionophores&
• "<2<=6<.*>#naturally#occur#
in#some#bacteria#and#are#
known#to#disrupt#one#portion#
of#the#electrochemical#
gradient#
Valinomycin*
• When#?3412<@A+12(B?34C#is#added,#K+#is#able#to#move#though#the#membrane#
• Protons#are#pumped#into#the#IMS#to#create#a#pH#and#electrical#gradient#
• Val,#as#a#result,#pumps#K+#into#the#matrix,#disturbing#the#electrical#gradient#
• With#each#proton#pumped#into#the#IMS#a#K+#is#pumped#into#the#matrix#
o Electrical#gradient#cannot#be#
maintained#
• However,#the#chemical#gradient#(pH#
gradient)#is#increased#
o Seems#that#the#electrical#
gradient#is#converted#to#pH#
gradient#by#pumping#more#
protons#
o This#keeps#the#energy#stored#
in#the#gradient#the#same#
Nigericin*
• D1E*.1+12#pumps#a#K+#into#the#IMS#while#pumping#a#proton#back#into#the#
matrix#
• There#is#no#proton#gradient#and#thus#the#chemical#gradient#collapses#
• Since#K+#does#have#a#positive#charge#the#electrical#gradient#is#still#maintained#
• More#proton#pumping#occurs#and#thus#more#K+#is#pumped#out#
o Essentially#the#energy#stored#is#kept#constant#by#increasing#the#
electrical#gradient#
Chemiosmotic-Driven&Transport&
• Transporters#importing#materials#into#the#matrix#for#the#Krebs#cycle#or#ETN#
use#different#parts#of#the#electrochemical#gradient#as#their#power#source#
• FG*2A43,*(,.32>=<.,*.>#transfers#ATP#into#the#cytosol#while#allowing#ADP#to#
enter#
