biochemistry 2 Flashcards
where does the link reaction take place
mitochondrial matrix
what are the 3 stages of the link reaction
1) decarboxylation
2) oxidation
3) transfer to CoA
what regulates the pyruvate dehydrogenase complex
- phosphorylation inactivates E1 site
- dephosphorylation activates E1 site
- high energy charge decreases activity and low energy charge increases activity
what causes arsenic poisoning
arsenic compounds react with sulfhydryl groups
- inactivates E2
how is oxaloacetate converted into citrate and how is it regulated
- additions of acetyl CoA
- regulated by substrate availability
- inhibited by citrate
how is citrate used as an inhibitor
inhibitor of phosphofructokinase-1
how is citrate converted into isocitrate
- isomerisation by aconitase
how is isocitrate converted into alpha-ketaglutarate
- oxidative decarboxylation - removal of CO2
- NAD+ to NADH
- isocitrate dehydrogenase
how is alpha-ketoglutarate converted into succinyl CoA
- addition of CoA
- CO2 removed
- NAD+ to NADH
- alpha-ketoglutarate dehydrogenase complex
how is succinyl CoA converted to succinate
- succinate thiokinase
- phosphorylation of either GDP to GTP or ADP to ATP
how is succinate converted into fumerate
- oxidation - FAD to FADH2
- succinate dehydrognase
what does succinate dehydrogenase reduce
flavin adenine dinucleotides
(FAD)
how is fumerate converted to malate
- addition of H20
- fumarate hydratase
how is malate converted into oxidate
- malate dehydrogenase
- NAD+ to NADH
what inhibits citrate synthesis
ATP and citrate
what inhibits and activates isocitrate dehydrogenase
- inhibited by ATP
- activated by ADP and NAD+
what inhibits alpha-ketoglutarate dehydrogenase complex
- succinyl CoA
- NADH
- ATP
what is anaolerotic reactions
- form intermediates to replenish other pathways
what does fluroacetate inhibit and cause
- inhibits aconitase
- nausea, vomiting, abdominal pain, sweating, confusion, tachycardia
what does arsenate inhibit and cause
- inhibits alpha-ketoglutarate dehydrogenase complex
- drowsiness, headaches, confusion, severe diarrhoea
what does malonate inhibit and cause
- inhibits succinate dehydrogenase
- headaches, fatigue, poor appetite, sleeplessness, tremours, confusion, mapped chains, coma, death
what does aluminium do to the TCA cycle
- displaces iron
- decreases activity of iron-dependent enzymes and oxidation sensitive enzyme activity
what are the iron dependent enzymes
aconitase
succinate dehydrogenase
fumerase
complex IV - electron transport chain
what are the oxidation sensitive enzymes
isocitrate dehydrogenase
alpha- ketoglutarate dehydrogenase
what is the outer mitochondria membrane permeable to
- small molecules - <10kDa
what is the inner mitochondrial membrane impermeable to
- protons - has specialised special transport proteins
where are respiratory chains found
- inner membrane
- 5 complexes
- has adaptors of coenzyme Q and cytochrome C
what is the function of respiratory chains
- allows flow of electrons
- generate a proton gradient
- produces ATP from FADH2 and NADH
what does complex I do
- accepts electrons from NADH
- passes these onto coenzyme Q
what does complex II do
- accepts electrons from FADH2
- passes these onto conezyme Q
what does complex III do
- accepts electrons from coenzyme Q
- passes these onto cytochrome C
what does complex IV do
- accepts electrons from cytochrome C
- reduces oxygen to water
what does complex V
- protons pass through the channel
- movement occurs
- drives ATP synthesis
what is complex V limited by
- ADP concentration
what are the inhibitors of the electron transport chain
- cyanide
- CO
- rotenone
- amytal
- abtimycin
- oligomycin
where do inhibitors bind in the electron transport chain
- binds to chain components
- block electron transfer
what does arginine react with and form
oxygen to from citruline and NO free radical
what do scavenger reactive oxygen species do
- protective enzymes
- help neutralise reative oxygen speciles
what does superoxide dismutase do
uses copper reactive centre to from intermediates - H2O2 and O2
what does peroxidase catalyse do
- uses a iron haem group to form intermediates - 2H2O and O2
what do reactive oxygen species do and what are they used for
- highly reactive and damaging
- from pollution, smoke, radiation and drugs
- used by phagocytes to kill cells
what do ionophores do
- activated by free fatty acids
- transport protons from the cytosol to matrix
what do uncouplers do
- transport protons across the inner mitochondrial membrane into the matrix
