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What's up everyone;
I'm working on some biochem homework and there's a question I'm having problem with. I'm hoping that someone here migh thave some insights. (the hw is mc form... so here is the question, possible answers, and my thoughts on those answers)
Q. What happens in a reductive decarboxylation rxn?
A. CO2 makes high engery bond with thiamine pyrophosphate (tpp)
-I think this is incorrect. My understanding is that TPP attacks pyruvate (at middle carbon) leading to the loss of CO2. Eventually Acytl-CoA is formed. The thing is that at no time do the CO2 and TPP bond (at least in my understanding)
B. The CO2 is reduced by the electron transport system to give 02 and CH4.
- This is just plain wrong.
C. CO2 is transfered to pyruvate giving oxaloacetate
-this would be a carboxylation, not a decarboxylation, right?
D. Release of CO2 is mechanistaclly coupled to the reduction of NAD+ to NADH
-i'm not familier with what pathway this would be in. it's my understanding that this is how the oxidative decarboxylations in the TCA cycle produce NADH, but I can't find any info for a reductive decarboxylation operating in this fashion.
So I've eliminated all of my answers.... HELP!!!
I'm working on some biochem homework and there's a question I'm having problem with. I'm hoping that someone here migh thave some insights. (the hw is mc form... so here is the question, possible answers, and my thoughts on those answers)
Q. What happens in a reductive decarboxylation rxn?
A. CO2 makes high engery bond with thiamine pyrophosphate (tpp)
-I think this is incorrect. My understanding is that TPP attacks pyruvate (at middle carbon) leading to the loss of CO2. Eventually Acytl-CoA is formed. The thing is that at no time do the CO2 and TPP bond (at least in my understanding)
B. The CO2 is reduced by the electron transport system to give 02 and CH4.
- This is just plain wrong.
C. CO2 is transfered to pyruvate giving oxaloacetate
-this would be a carboxylation, not a decarboxylation, right?
D. Release of CO2 is mechanistaclly coupled to the reduction of NAD+ to NADH
-i'm not familier with what pathway this would be in. it's my understanding that this is how the oxidative decarboxylations in the TCA cycle produce NADH, but I can't find any info for a reductive decarboxylation operating in this fashion.
So I've eliminated all of my answers.... HELP!!!
