Simple Vs. Conjugated Proteins - Online Tutor, Practice Problems & Exam Prep

Simple proteins consist solely of amino acid residues, while conjugated proteins contain additional non-amino acid components known as prosthetic groups. There are six classes of conjugated proteins, differentiated by their prosthetic groups: lipoproteins (fatty acids), glycoproteins (carbohydrates), phosphoproteins (phosphate groups), hemoproteins (heme groups), flavoproteins (flavonucleotides), and metalloproteins (metal ions). Understanding these classifications is essential for grasping protein structure and function in biological processes.

Simple Vs Conjugated Proteins

In this video, we're going to distinguish between simple and conjugated proteins. So the difference between simple and conjugated proteins is actually pretty simple. Simple proteins are literally simple because they only contain amino acid residues, but they have no other chemical components. Now, conjugated proteins, on the other hand, are proteins that, of course, contain amino acid residues, because you can't be a protein without having amino acid residues. But conjugated proteins also contain other permanently associated chemical components that are not amino acid residues. These other chemical components are called prosthetic groups. The definition of prosthetic groups are just tightly bound, non-amino acid components or parts of a conjugated protein. In our example down below, we can distinguish better between the simple and conjugated proteins.

On the left over here, what we have is an image of an enzyme known as chymotrypsin. Chymotrypsin is a peptidase or an enzyme, that breaks down the peptide bonds of other proteins. Later in our course, we're going to talk a lot more details about chymotrypsin's structure and function. But for now, what I want you guys to know is that chymotrypsin is an example of a simple protein. The reason that it is a simple protein is because chymotrypsin only contains amino acid residues, but no other chemical components. When we look at chymotrypsin structure, we can see that there are alpha helices, beta pleated sheets, loops, and beta turns, but we don't see any other signs of other chemical components that are not amino acid residues. That's what makes chymotrypsin a simple protein.

Now over here on the right, notice we have a hemoglobin protein shown. We've talked about hemoglobin multiple times in our previous videos. We know that hemoglobin is a heterotetramer, or a protein with four subunits. We can see that we have one subunit over here that is identical to this other subunit over here, and then we have these other two subunits that are identical to each other, but different from the yellow subunits. That's what makes hemoglobin a heterotetramer. What you'll notice is, throughout the hemoglobin structure, there are these discs here, these yellow discs. And we can tell because when we zoom in on it over here, we can see that there are iron atoms in the center, there are all of these cyclic carbon rings, and there are all of these double bonds. It does not have the typical structure of an amino acid, which means that it is not an amino acid. And because this chemical component that is not an amino acid is associated with the protein, that makes it a prosthetic group. More specifically for hemoglobin, this prosthetic group is known as a heme group. Later in our course, we're going to talk a lot more details about hemoglobin structure and function. But for now, what I want you guys to know is that because hemoglobin has this prosthetic group that is a non-amino acid chemical, that makes hemoglobin a conjugated protein. And there are other proteins out there that contain non-amino acid prosthetic groups like hemoglobin.

This concludes our lesson on the difference between simple proteins and conjugated proteins. In our next practice video, we'll be able to get some practice applying these concepts. So I'll see you guys there.

Which of the following images shows a conjugated protein?

• A. Trypsin.
• B. Insulin.
• C. α-keratin.
• D. Myoglobin.

Simple Vs Conjugated Proteins

So now that we know the difference between simple and conjugated proteins, we can talk about the classes of conjugated proteins. It turns out that there are 6 main classes of conjugated proteins. These 6 main classes differ by their prosthetic groups. In our example below, you'll see we have a table here of the 6 classes of conjugated proteins. You don't need to memorize all of these classes right now, but throughout our course, we're going to be talking about enzymes and proteins that fall under each of these classes of conjugated proteins. It's good to start familiarizing yourself with these classes. For our first class of conjugated protein, we have the lipoproteins. This enzyme is critical in fatty acid metabolism or the breakdown of fats such as triglycerides. We'll talk about this when we get to fatty acid metabolism later in our course.

Our second class of conjugated proteins are the glycoproteins, and the glycoproteins' prosthetic group is just a carbohydrate. They are carbohydrates. An example is immunoglobulin G or IgG, which is an antibody, and we'll talk a lot more about antibodies later in our course as well. Our third class of conjugated proteins are the phosphoproteins, and the prosthetic group is going to be a phosphate group. An example of a phosphoprotein is phosphoprotein phosphorylase 1 or PP1. This enzyme is important in regulating glycogen breakdown, and we'll talk about it more later in our course as well.

Our fourth class of conjugated proteins are the hemoproteins. The hemoproteins have a prosthetic group of just a heme group, which also contains an iron porphyrin molecule. We'll talk more details about this heme group later in our course as well. Examples are myoglobin and, of course, hemoglobin. We'll talk more again about myoglobin and hemoglobin later on in our course.

Our fifth class of conjugated proteins is going to be our flavoproteins. Our flavoproteins have prosthetic groups of just flavin nucleotides, for example, FAD. Our example of a flavoprotein is succinate dehydrogenase, and we'll talk about this enzyme more when we talk about the citric acid cycle and the electron transport chain later in our course.

And then our last class of conjugated protein is going to be our metalloproteins. Our metalloproteins are going to be prosthetic groups of just metals. So what you see here is that we have a bunch of metals listed, like, for example, iron, zinc, calcium, molybdenum, copper, and so all of these metals here are examples of prosthetic groups of metalloproteins. Examples include ferritin, alcohol dehydrogenase, calmodulin, dinitrogenase, and plastocyanin. We'll be talking about different metalloproteins throughout our course as well.

So again, just try to familiarize yourself with these classes that are here and their prosthetic groups, and we will talk about these enzymes throughout our course. This concludes our lesson on the classes of conjugated proteins, and we'll get a little bit of practice in our next video. So I'll see you guys there.

Which of the following classes of conjugated proteins does the following protein fall into?

• A. Hemoprotein.
• B. Flavoprotein.
• C. Simple protein.
• D. Metalloprotein.

Here’s what students ask on this topic:

What is the difference between simple and conjugated proteins?

Simple proteins consist solely of amino acid residues and do not contain any other chemical components. In contrast, conjugated proteins also contain amino acid residues but have additional non-amino acid components known as prosthetic groups. These prosthetic groups are tightly bound and can include various chemical entities such as lipids, carbohydrates, phosphates, heme groups, flavonucleotides, or metal ions. Understanding this distinction is crucial for studying protein structure and function in biological processes.

What are the six classes of conjugated proteins?

The six classes of conjugated proteins are differentiated by their prosthetic groups. They include: 1) Lipoproteins, which have fatty acid prosthetic groups; 2) Glycoproteins, with carbohydrate prosthetic groups; 3) Phosphoproteins, containing phosphate groups; 4) Hemoproteins, which have heme groups; 5) Flavoproteins, with flavonucleotide prosthetic groups; and 6) Metalloproteins, which contain metal ions such as iron, zinc, calcium, molybdenum, and copper. Each class plays a unique role in various biological processes.

What is a prosthetic group in conjugated proteins?

A prosthetic group in conjugated proteins is a non-amino acid component that is tightly bound to the protein. These groups are essential for the protein's function and can include a variety of chemical entities such as lipids, carbohydrates, phosphates, heme groups, flavonucleotides, or metal ions. Prosthetic groups play a critical role in the protein's biological activity and stability.

Can you provide examples of simple and conjugated proteins?

An example of a simple protein is chymotrypsin, which consists solely of amino acid residues and lacks any additional chemical components. On the other hand, hemoglobin is an example of a conjugated protein. It contains amino acid residues and a prosthetic group known as a heme group, which includes an iron atom. The presence of this non-amino acid component classifies hemoglobin as a conjugated protein.

Why is hemoglobin considered a conjugated protein?

Hemoglobin is considered a conjugated protein because it contains a prosthetic group known as a heme group. This heme group includes an iron atom and is essential for hemoglobin's function in oxygen transport. The presence of this non-amino acid component, tightly bound to the protein, distinguishes hemoglobin from simple proteins, which consist solely of amino acid residues.