succinate dehydrogenase (SDH)

Question 1

In this rxn…

Answer 1

in the TCA we have seen NADH made, but now wee making FAD..
Why? oxidation of an alkane to alkene is exergonic enough that i can reduce FAD but not NAD+…. dont have enough oomph to do this reduction on NAD+ so must do it on FAD.

Question 2

When would. use NAD+

Answer 2

when oxidizing an OH… not doing that in this rxn so use FAD

Question 3

FAD

Answer 3

enzyme bound, prothestic group.

tightly, noncovalently bound

Question 4

CoQ/CoQH2

Answer 4

ubiquinone, molecule that is used as a mobile e- carrier in ETC.
In this situation, enzyme is different.
CoQ reoxidizes SDH bound FADH2…. CoQ gets reoxidized by the ETC.

Question 5

SDH

Answer 5

only membrane bound TCA enzyme (all rest are in matrix)…
part of complex II of ETC, which is the flavoprotein portion.

Question 6

Succinate being symmetryical

Answer 6

2 consequences
Need to know there are Hydrogens lost, one as H+ other than H-.

One is from HS, one is HR from the other center. DOESNT MATTER WHICH IS WHICH, JUST THAT THEYRE BOTH LOST

2 Consequences:
1. can go in either way to AS of enzyme
2. Can no longer track which Carbons came from this turns acetyl-coA that was added….

half of the C;s could be put in from one direction or the other…..

this leads us to the A PRIOR turn because now we dont now if this particular molecule is removing carbons that were added in the previous one or the one prior to that