Myoglobin is a protein containing 153 amino acids. Approximately half of the amino acids in myoglobin have polar side chains.
a. Where would you expect these amino acid side chains to be located in the tertiary structure of the protein?

Question

Myoglobin is a protein containing 153 amino acids. Approximately half of the amino acids in myoglobin have polar side chains.

a. Where would you expect these amino acid side chains to be located in the tertiary structure of the protein?

Accepted Answer

All right. Hello everyone. So this question says that an enzyme consists of 250 amino acids with nearly 55% being polar considering its function in a cellular aqueous environment. Where would these polar amino acids predominantly be located in the enzyme's tertiary structure option? A says uniformly distributed throughout the enzyme B says on the exterior surface of the enzyme C says within the hydrophobic core of the enzyme and D says only near the substrate binding site. So first and foremost, we call it the tertiary structure of a protein is characterized by interactions between amino acid side chains. And so because these side chains can be characterized in different ways depending on their polarity. For example, different interactions are possible. Now, it's important to recognize that a protein has to be able to mix well with its environment, otherwise it won't be able to perform its function. So, one of the main interactions that we study here are called hydrophobic interactions. And this is where the nonpolar amino acids inside of a protein inside of a polypeptide tend to cluster together to avoid interaction with the abes environment as much as possible. And So we end up with a very characteristic structural pattern. So let's say that I have this aqueous environment. Let's say that this is the cell with aqueous fluid inside of it. And so here, as mentioned before, in order for these nonpolar amino acids to avoid interacting with that aqueous environment, they're going to cluster around the center of the protein away from the aqueous environment. This means that the hydrophilic amino acids, the polar amino acids are going to primarily make up the exterior of the protein interacting with the aqueous environment and protecting the nonpolar amino acids in the center. And so like this, all of the amino acids are happy, they're interacting with their preferred environment. And so this means that our correct answer here is going to be option B in the multiple choice because the polar amino acids are more likely found on the exterior surface of the enzyme. Now just a quick note about option d in the multiple choice near the substrate binding site. This one is a little uncertain because the properties of the binding site depends heavily on the substrate of that particular enzyme. And we don't have any information about that. So here in any case, we know that polar amino acids are going to occupy the exterior so that they can interact with the water molecules in the environment. So B is our answer. And so there you have it with that being said, thank you. So very much for watching and I hope you found this helpful.

Myoglobin is a protein containing 153 amino acids. Approximately half of the amino acids in myoglobin have polar side chains.
a. Where would you expect these amino acid side chains to be located in the tertiary structure of the protein?

Verified video answer for a similar problem:

Key Concepts

Tertiary Structure of Proteins

Polar and Nonpolar Amino Acids

Hydrophobic Effect

Myoglobin is a protein containing 153 amino acids. Approximately half of the amino acids in myoglobin have polar side chains.a. Where would you expect these amino acid side chains to be located in the tertiary structure of the protein?

Verified video answer for a similar problem:

Key Concepts

Tertiary Structure of Proteins

Polar and Nonpolar Amino Acids

Hydrophobic Effect

Myoglobin is a protein containing 153 amino acids. Approximately half of the amino acids in myoglobin have polar side chains.
a. Where would you expect these amino acid side chains to be located in the tertiary structure of the protein?