The reaction that follows is catalyzed by isocitrate dehydrogenase and occurs in two steps, the first of which (step A) is formation of an unstable intermediates (shown in brackets).
c. Which of the structures shown can be described as a β-keto acid?

Question

The reaction that follows is catalyzed by isocitrate dehydrogenase and occurs in two steps, the first of which (step A) is formation of an unstable intermediates (shown in brackets).

c. Which of the structures shown can be described as a β-keto acid?

Accepted Answer

Welcome back, everyone consider the following reaction catalyzed by mala dehydrogenase, which structure in the equation can be described as a beta keto acid. Before we begin this problem, let's simply understand what a beta keto acid is. First of all, let's draw carboxyl, we know that carboxylic acids have co oh functional group and their structure. And then we can have multiple carbon groups are basically multiple carbons bonded to our Carboni. Right? Specifically, if we consider a stray chain, we can classify our carbons as follows. The first carbon bonded to carbonyl is classified as an alpha carbon. The second one would be beta, the third one would be gamma and so on. So, in this specific problem, we understand that we have a beta keto acid, which essentially means that the beta carbon forms carbonyl and specifically, it's a keto acid, right, which means that this specific carbonyl must be bonded to two adjacent carbons. So our goal is to identify such a structure in this problem. Let's begin with L Mala. And specifically what we notice is that we do not have any beta keto acid. And the reason is very simple, even though we have carboxylate ions, we can clearly see that there is no carbel in the structure, right? Essentially we have siege two followed by cho H. Now, on the product side, when reaction A takes place, we are producing oxalacetate and we have two carboxyl groups coo negative. Of course, this acid is deproteinate, right. So we can consider it coo h in its acidic form. And now what we notice is that relative to that coo negative, the alpha carbon has carbona. So that would be alpha keto acid because at the beta position, we have CH two, right. So at the beta position, we do not have carbona. So relative to that specific coo negative, this is not a beta keto asset, but we have to be very careful because there's another herb boxy late. And now if we look at our carbons, the alpha carbon is CH T and then at the beta carbon, we have car bono that carbonyl is bonded to two adjacent carbons. So indeed, oxalacetate is a beta keto acid. And now pyro is the final structure that we want to consider. We have co negative. And we see that the alpha carbon is carbonel and the beta carbon is a methyl group. So it is not a beta keto acid. It is actually an alpha keto acid because Carboni is at the alpha carbon relative to carboxylate. Therefore, we can conclude that for this specific problem, the answer would be oxalacetate. It is a beta keto acid. Thank you for watching.

The reaction that follows is catalyzed by isocitrate dehydrogenase and occurs in two steps, the first of which (step A) is formation of an unstable intermediates (shown in brackets).

c. Which of the structures shown can be described as a β-keto acid?

Verified video answer for a similar problem:

Key Concepts

Isocitrate Dehydrogenase

ß-Keto Acid

Unstable Intermediates

The reaction that follows is catalyzed by isocitrate dehydrogenase and occurs in two steps, the first of which (step A) is formation of an unstable intermediates (shown in brackets).c. Which of the structures shown can be described as a β-keto acid?