BIOC13H3 Lecture Notes - Lecture 11: Pentose Phosphate Pathway, Pyruvate Carboxylase, Futile Cycle
29 Apr 2018
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!"#$%&'()*+,-.*(%/( ( 012,*.3(4(
5*6(%78(4/%9(
31#
Gluconeogenesis+and+Pentose+Phosphate+
Pathway!
Gluconeogenesis+
• :;-+<=*<>*=*?1?#is#the#process#of#
making#glucose#from#a#non-
carbohydrate#precursor#
• Important#during#fasting/starvation,#
when#you’ve#exhausted#your#glycogen#
storage#
• Precursors#include:#
o Glycerol#from#the#fatty#acid#
backbone#can#be#converted#into#
DHAP#
o Lactate#can#be#converted#back#
into#pyruvate#
o Amino#acids#can#be#metabolized#
into#oxaloacetate#
§ Leucine#and#lysine#cannot#
go#though#this#
• 3#things#need#to#happen:#
o Pyruvate#needs#to#be#reduced#
into#glucose#
o ATP/GTP#needed#to#drive#
process#
o Electron#needs#to#be#added#to#pyruvate#(taken#from#NADH)#
• There#are#4#unique#enzymes#(ie.#not#also#involved#in#glycolysis)#
o Prevents#futile#cycles#by#making#process#irreversible#
o We#will#be#focusing#on#those#enzymes#since#energetics#of#the#others#are#
pretty#easy#to#figure#out#
Reactions+of+Gluconeogenesis+
!"#$%&'()*&#+,-".&/()0122"),3)'41/)/.15(6)
• Converts#pyruvate#into#oxaloacetate#using#CO2#
• ATP#is#broken#down#to#provide#the#energy#to#do#so#
o Energy#is#conserved#in#that#oxaloacetate#
• Atmospheric#CO2#is#low,#making#it#unfavourable#to#use#
• Since#CO2#is#a#gas,#entropy#is#reduced#and#therefore#there#is#more#free#energy#
in#the#oxaloacetate#
• The#pyruvate#carboxylase#has#3#domains#
o !1<,1=([email protected]<AB;@,1<=(C!$D(2<3@1=#is#where#the#reaction#begins#
§ CO2#is#phosphorylated#to#create#high#energy#[email protected]<AB;EF<?EF@,*#
Document Summary
Gluconeogenesis: gluconeogenesis is the process of making glucose from a non- carbohydrate precursor. Important during fasting/starvation, when you"ve exhausted your glycogen storage: precursors include, glycerol from the fatty acid backbone can be converted into. Dhap: lactate can be converted back into pyruvate, amino acids can be metabolized into oxaloacetate. Co2 is phosphorylated to create high energy carboxylphosphate. Cori cycle: once you"ve exhausted all carbohydrates, need another way to make glucose, very important during intense exercise since muscles uses glucose and lactate fermentation as the quickest way to make. Atp: lactate fermentation results in change in blood ph which makes the liver able to take up lactate to make glucose the. Anabolic glucose oxidation: pentose phosphate pathway (ppp) is an anabolic glucose oxidation pathway, occurs in the cytosol making it likely to be an ancient pathway, broken down into 2 main phases. Ppp activity: there are three goals of the ppp, nucleotide synthesis where r5p is converted to ribose-5-p.
