Serotonin is a monoamine neurotransmitter. It is formed in the body from the amino acid tryptophan (Figure 28.6, p. 836). What class of enzyme catalyzes each of the two steps that convert tryptophan to serotonin?

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Hello, everyone. Let's take a look at this next question. The conversion of dopamine to norepinephrine is a key step in catecholamine biosynthesis. What class of enzyme catalyzes the conversion of dopamine to norepinephrine? And we're given a diagram of the structures of the two molecules. And then four answer choices. A oxidoreductase, oxidoreductase B hydrolysis C lias or D transfer AIS. So first, we need to look carefully at the changes occurring with this reaction and and think about what class of enzyme might catalyze that type of change. So let's look at our two molecules and we compare dopamine and norepinephrine. We see they both have an aromatic ring with two hydroxyl groups in the same position on that ring. And then a longer amino chain dopamine just has ch two ch two NH two on that chain, norepinephrine has that same chain, but there's an additional hydroxyl group. So the reaction that we see here is the addition of a hydroxyl group. Now, what type of that reaction? W what type of reaction would that be? Well, what was originally on the dopamine at that same carbon? Well, originally there would have been two hydrogens. Now we have one hydrogen and 10 group. So we've lost a hydrogen and gained ac O bond. So when you remove hydrogens and or add hydro oxy co bos add oxygens you are talking about and oxidation. And this is indeed an oxidation reaction. If we want to fine tune this diagram on our reaction arrow. We draw a little swooping arrow there showing that we have 02 molecular oxygen as a reactant being converted to a molecule of water. So we have one oxygen atom from that 02 being added to our dopamine. And then we have the other atom of oxygen becoming water. So this is the reduction reaction. Let's look up here. So they are the reduction of that oxygen to water and then the oxidation of dopamine. So we have an exchange of electrons going on here. We have a redox reaction. And the kind of enzymes that carry that out of the class of enzymes are choice a oxidoreductase as pretty logical often enzyme names give us a clue there. So those oxy over duc aes are enzymes that catalyze catalyze redox reactions. The transfer of electrons from one atom to another. Let's look briefly at our other answer. Choices. Oh And to be thorough, we can add the name of this enzyme, this oxido reductase, which in this case is dopamine beta hydroxylase. But our question doesn't ask us that that'll just be an extra throw here. So let's touch briefly on our other answer choices and why they are incorrect choice. B hydrolysis. These would be enzymes that catalyze bond cleavage by means of adding a water molecule. In other words, hydrolysis reactions. But as you can see, we're not using up water, we're generating water as a product of our reaction. So, hydrolase is not correct here to see lice. These are enzymes that catalyze the breaking of chemical bonds by means other than hydrolysis or redox reactions. So this is not the case here because we have a redux reaction occurring. So it's not the yass and then finally there d transfer ais well as their name suggests, these are in subs that catalyze the movement of a group. So that one's pretty easy to remember, we can think of transferring a functional group but that's not what's happening here. So we'll cross that off. So again, when we look at this reaction that involves the conversion of dopamine to norepinephrine that the class of enzyme that catalyzes this conversion. So not the specific enzyme but class is choice a oxidoreductase. See you in the next video.

Serotonin is a monoamine neurotransmitter. It is formed in the body from the amino acid tryptophan (Figure 28.6, p. 836). What class of enzyme catalyzes each of the two steps that convert tryptophan to serotonin?

Verified Solution

Key Concepts

Monoamine Neurotransmitters

Tryptophan

Enzymatic Catalysis