Lecture 307: respiratory chain Flashcards
mitochondria uses O2 to regenerate ____
- NAD+ so all rxns can continue to synthesize NADH
glucose oxidation
- 12 reducing equivalents produced [10 NADH and 2FADH2]
- need 1/2 O2 per reducing equivalent
- H2O used and synthesized
NADH and FADH2 can be converted to ___ molecules of ATP
- 32
NADH
- main donor of e- in cells
- readily dissociates from enzymes [carries e- between enzymes so substrates can be ox/ red]
- can carry ONLY TWO e- at a time
- main donor in oxidative phosphorylation
PDH complex and TCA cycle occur in
- mitochondrial matrix
e- transport and oxidative phosphorylation occur in ___; also includes ___
- inner membrane
- succinate-dehydrogenase from TCA cycle [involved in e- transport]
reduction e- carriers for energy production in respiratory chain
- NADH or FADH2
- complex 1-4 [multiprotein enzyme complexes]
- CoQ
- cytochrome C
flavoproteins
- tightly bound FMN or FAD
- can link 1 OR 2 e- at a time
- complexs 1 and 2
iron-sulfur proteins
= non-heme iron complexed with sulfur
- Fe-S = 1 iron complexed with 4 cysteine residues
- Fe4-S4 = 4 iron, 4 inorganic sulfur, 4 cysteine residues
- iron = e- carrier [Fe2+ or Fe3+]
- complexes 1, 2 and 3
CoQ
- can link 1 OR 2 e-
- lipophilic = located in inner membrane of mitochondria
cytochromes
= specific group of heme proteins [heme covalently bound]
- can be a, b or c-types
complexes as a, b or c-type cytochromes
- complex 2 = b-type
- complex 3 = b and c-type
- complex 4 = a-type [a1 or a3]
cytochrome b and c-types contain what kind of heme
- same heme found in hemoglobin
cytochrome a-type contains what kind of heme
- heme variant heme-A = associated with copper ion
all heme-bound iron cycles through ___ and ___ bound states
- +3
- +2
copper ions associated with heme-a cycle through ___ bound states
- +1
- +2
transport of e- is a series of coupled (endergonic/ exergonic)
- exergonic
complexes 1, 3 and 4 as proton pumps
= energy USED [from free e-] to pump protons UP their gradient from matrix into intermembrane space
complex 5 as a proton pump
= GENERATES energy as protons are pumped DOWN their gradient from intermembrane space to matrix
complex 1
= NADH-CoQ reductase
- 45 subunit complex
- contains one bound FMN and 8Fe-sulfur clusters
- PROTON PUMP = transports 4H+ into intermembrane space
complex 2
= succinate-CoQ reductase [succinate dehydrogenase complex (flavoprotein; TCA cycle enzyme)]
- 4 subunit complex
- contains 3 Fe-sulfur clusters
- CoQ draws from succinate [e- transferred ONE at a time]
- NOT a proton pump = NO H+ transfer
function of CoQ in complex 2
= helps regenerate FAD within the succinate dehydrogenase enzyme = enzyme can keep functioning in TCA cycle
both complex 1 and 2 end up dumping e- to ____
- CoQ
complex 3
= CoQ: cytochrome c oxidoreductase
- dimer = 10-11 subunit complex
- 2 binding sites = Q0 and Q1 [travels from 0 to 1]
- IS a proton pump = transports 4H+ into intermembrane space
- transfers e- to cytochrome c = each only carries ONE e- each
