If each of the following amino acid side chains is present in the active site of an enzyme, indicate whether it would (a) serve a catalytic function, (b) serve to hold the substrate, or (c) both.
d. lysine

Question

If each of the following amino acid side chains is present in the active site of an enzyme, indicate whether it would (a) serve a catalytic function, (b) serve to hold the substrate, or (c) both.

d. lysine

Chemical structure of lysine with a positively charged amino group, relevant to enzyme function in biochemistry.

Accepted Answer

All right. Hello everyone. So this question says if an enzyme contains an isoleucine side chain in its active site indicate its probable function. Option A says it serves a catalytic function. B says it serves to hold the substrate. C says both and B says neither. So first and foremost, what does isoleucine look like? What are the properties of isol lucine? Well, recall that isoleucine that's ile for short is a nonpolar, oops, it is a nonpolar hydrophobic amino acid. So it's nonpolar, it's hydrophobic and the reason it is is because it has an ocular side chain. So the side chain is just a hydrocarbon chain. So now what does this mean for the function of isoleucine especially in the active site of the enzyme? Well, first of all, going back to option A here, what does it mean for an amino acid to have a catalytic function? Well, there are multiple different types of catalytic functions that are possible, right? We can talk about acid base reactions, we can talk about nucleic attack and we can also talk about the role or potential role of an amino acid in stabilizing the transition state just holding it where it needs to be in the active site that is also considered a catalytic function. Now, the thing is though is that in order for an amino acid to potentially assist with these catalytic functions, there has to be some kind of polar side chain. This is because the side genes that can participate in nucleic attack and acid base reactions, for example, are typically going to be polar because they contain hetero atoms. And so because this is not true of isoleucine isoleucine doesn't have any polar functional groups. It cannot serve a catalytic function. And so what is the role of a nonpolar amino acid such as is Soucy? Well, a not polar side chain can interact with other non polar groups. And so what that means is that the side chain of isoleucine could potentially interact with the non polar regions of the substrate. And so that helps to stabilize the substrate in its own way, right? By encouraging these hydrophobic interactions between the substrate and the active site through the isoleucine side chain, it helps to hold the substrate where it should be. So this means that our answer is going to be option b in the multiple choice because isoleucine would most likely serve to hold the substrate because it cannot participate in any catalytic activity. So there you have it. And with that being said, thank you so very much for watching. And I hope you found this helpful

If each of the following amino acid side chains is present in the active site of an enzyme, indicate whether it would (a) serve a catalytic function, (b) serve to hold the substrate, or (c) both.
d. lysine

Verified video answer for a similar problem:

Key Concepts

Amino Acid Side Chains

Enzyme Active Site

Catalytic Function vs. Substrate Binding

If each of the following amino acid side chains is present in the active site of an enzyme, indicate whether it would (a) serve a catalytic function, (b) serve to hold the substrate, or (c) both.d. lysine

Verified video answer for a similar problem:

Key Concepts

Amino Acid Side Chains

Enzyme Active Site

Catalytic Function vs. Substrate Binding

If each of the following amino acid side chains is present in the active site of an enzyme, indicate whether it would (a) serve a catalytic function, (b) serve to hold the substrate, or (c) both.
d. lysine