A substrate is held in the active site of an enzyme by attractive forces between the substrate and the amino acid side chains. For the outlined regions A, B, and C on the following substrate molecule:
b. Could the amino acids serine, lysine, or glutamate be present in the active site? Support your answer.

Question

A substrate is held in the active site of an enzyme by attractive forces between the substrate and the amino acid side chains. For the outlined regions A, B, and C on the following substrate molecule:

Diagram showing a substrate molecule with labeled regions A, B, and C, illustrating enzyme-substrate interactions.

b. Could the amino acids serine, lysine, or glutamate be present in the active site? Support your answer.

Accepted Answer

Hi, everyone and welcome back. Let's look at our next question here. The substrate shown below was discovered to be held by some amino acid side chains in enzymes active site. Can the amino acids, phenyl alanine, valine and lysine be found in the active site? Why? And our substrate is not named here. But if you look at it, you can see that it's benzoate, there's a benzene group with a carboxylate group. Attached note that the carboxylate group as the is in the negatively charged form. So what we need to do is look at the structure. Look specifically, there are groups of the amino acids were being asked about to see whether it would be plausible that they would have interactions with the benzoate while it's in the active site. So first of all fel alanine, so Phelan's, our group is a benzene ring. So that would definitely have interactions with the benzene ring here. So it can have hydrophobic interactions and I can have what's called pie stacking, which is a non covalent attraction between aromatic rings. So that would definitely be possible interactions between phenylalanine residues and our substrate in the active site. So phenylalanine could be found in that site. Now, let's look at Vaile bing is another hydrophobic amino acid R group. So definitely we'll look at a hydrophobic interactions. Bing has an isopropyl group as its R group. So we have again, hydrophobic interactions possible with that aromatic ring. And then finally, lysine and lysine is one of the basic amino acids, oops it has four ch two groups and then an NH three plus group. So it's positively charged and notice that our benzoate has a negatively charged in our oxygen. So that could have interaction with that negatively charged group. So, lysine also could be expected to be an active site. So when we look at this benzoate subs stream and say, what would we find in the active site, would we expect to see the amino acids, phelan valine and lysine? And the answer is yes, because we could expect to see interactions between these amino acid residues, hydrophobic interactions and pie stacking with our phenylalanine residue, hydrophobic interactions with our veiling residue and then interactions between the positive charge on our lysine residue and a negative charge on our benzoate. See you in the next video.

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Key Concepts

Enzyme-Substrate Interaction

Amino Acid Properties

Active Site Specificity