gluconeogenesis from pyruvate-> labeling carbon

November 23, 2010 at 4:30 pm #14173

Participant

I have to predict the positions of the glucose molecule that would become labeled from the 1-14C pyruvate (i.e, the label in the carboxyl group of pyruvate).

a) Carbon-1

b) carbon-2

c) carbon-3

d) carbon-4

e) carbon-5

d) carbon-6

I first thought that carbons 1 and 6 were the correct answers, but they are not. Then I thought that 1,3,and 6 were correct but they are not. I know that pyruvate has 3 carbons and glucose has 6, but I know two how to approach this problem correctly. Any help will be appreciate it.

Thank you and happy holidays!

November 23, 2010 at 6:05 pm #102412

JackBean

Participant

look on the reactions, which take place in gluconeogenesis and their mechanism. It’s quite simple to trace the labeled atom…

November 23, 2010 at 7:10 pm #102413

nickname

Participant

So for this kind of problem you look at where the new carbon is being attached to, correct?

November 24, 2010 at 8:20 am #102429

JackBean

Participant

look on this picture: http://upload.wikimedia.org/wikipedia/e … enesis.png
and trace your atom! Just be carefull about symetrical molecules!

November 24, 2010 at 7:34 pm #102448

USFBiomed

Participant

3,4… its a head to head bonding, not tail to tail, so 1,6 would be the reverse…

November 24, 2010 at 7:55 pm #102451

nickname

Participant

Thank you USFBiomed. So since pyruvate is 3 carbons and glucose is 6 I connect the last of pyruvate with the first incoming carbon atom so 3 and 4 like you said. Is this explanation correct? Thanks again for your help and happy holidays!

April 24, 2015 at 11:46 pm #115707

Moleculeus

Participant

When the two triosephosphates condense head-to-head to form a hexose, carbon 1 of the triose (originating from the carboxyl of pyruvate) forms carbons 3 and 4 of the hexose, carbon 2 of the triose forms carbons 2 and 5 of the hexose, and carbon 3 of the triose forms carbons 1 and 6 of the hexose.

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