Altering Primary Protein Structure

in this video, we're gonna talk about altering primary protein structure. So recall that primary protein structure consists of both amino acid composition and the sequence of amino acid residues in a chain from the N terminal end to the C terminal in. And because that's true, primary protein structure can actually be altered by changing either the composition or the sequence. It doesn't matter which one you change. If you change one or the other, you're gonna be changing the primary protein structure. And really, it's really interesting because proteins air so sensitive that all it takes is just a single amino acid change. Um, and that could potentially cause a protein tau lose its shape and function. So it's not guaranteed that a single amino acid change will change the protein shape and function. But it could change, and so most proteins have thousands of amino acids in them, so they're pretty long proteins in nature. But changing just one amino acid could change the overall shape and structure for all 1000 of those amino acids, so you can see how sensitive ah, protein shape and structure is to the protein, primary protein structure and so down below. What we have is a diagram showing you how the primary protein structure could be altered. So at the very top, what we have is the original pro primary structure of a protein in this blue box way up here, and so noticed that the original sequences just Mathias unveiling, glazing final Alan, Alan ing and glycerine from the N terminal to the C terminal. And so there are two ways to change the primary protein structure. The first is to change the composition, and so there are really two ways to change the composition. You can either remove or add amino acids, or you could substitute amino acids. And so when you remove an ad, amino acids. So going this way here, the composition. You can see that in this example here, what we've done is we've removed the very end amino acids. So we've taken this glazing, and we've removed it from the sequence so noticed that the glazing is no longer here, and so that is one way to change the composition. The sequenced or the order of amino acids is still pretty much the same. You can see that it's still the same order of amino acids. It's just that we've removed the one at the end. This is still considered a change in the primary protein structure, and so the same goes for substituting amino acids. So notice here we have a female Alan ing and it's been substituted within a Spartak asset. And so that is an example of a substitution, and we're changing. The composition were also arguably changing. The sequence by, um, change making an amino acid substitution because the order is not the same. So the interesting thing is, that sequence kind of entails and includes composition. But composition does not entail and include sequence. So there are those slight differences between them. And so the second way to change the Amina um, the primary protein structure is to change the sequence, So change the sequence. I remember the sequence is the specific order of amino acids. And so if we go this way and we change the sequence, the way to change the sequence is to just rearrange the amino acids. And so if you have the same composition, so we're not changing the composition here, but we're change. We're rearranging the amino acids, so it's the same number and the same types of amino acids in this example. Down here, it's just that we've changed the order. So instead of Matthias coming first, we have final Allen in coming first. And so, uh, by rearranging them. That's an example of changing the sequence but not changing the composition. So basically either change the composition or sequence will change the or alter the primary protein structure and altering primary protein structure. Either may it may, or it may not alter the proteins final shaper function. It's gonna depend from situation to situation and from protein, a protein. So just keep in mind that it could cause the protein to change shape or function. And so this concludes this lesson here, and I'll see you guys in our practice video.

True or false: The following proteins with identical composition are certain to have the same shape/function.

Protein #1: L-G-T-V-R-D                        Protein # 2: D-R-V-T-G-L

• A. True
• B. False

in this video, we're going to talk about substituting amino acids. And it's interesting because if the substitute amino acid has similar properties to the original amino acid that's being replaced, then it's actually gonna be less likely for it to cause a drastic change. And so perhaps the protein will retain its overall shape and its function if you substitute with an amino acid that has similar properties. And so let's take a look at our example below, which asks which amino acids substitute is least likely to impact the protein's shape and function if it's substituted with a veiling. And so here we have our protein and noticed that the veiling here is right here, and so are options for substituting with veiling are below with these options. And so basically, the strategy for this is to remember our groupings and are no Monix for grouping the the amino acids. And so remember, for the non polar amino acids, it's Gavle limp and veiling. Here it's one letter code is V, and so it falls into the gavlin pits. Right here is veiling, so it is a non polar amino acid. And so if we're trying to had the less least likelihood of impacting the protein shape and function. With the substitution, we're gonna want the amino acid to be a non polar amino acid. And so, looking at these answer options down below, what you'll see is that a Spartak acid, which is D, is a negatively charged acidic amino acid. And so is glue tannic acid, which is also down here. And histamine is H, which is a positively charged amino acid. And so the only one that falls under the non polar amino acid is going to be is a Lucy, which is up here. So they both fall into the same category. And so what that means is, is a losing of these four options is going to be the one that's gonna have the lead that's gonna be least likely toe impact the proteins, overall shape and function if it's substituted with the veiling here. And so, uh, this concludes this lesson and I'll see you guys in our practice videos where we're gonna be able to get some practice with this so I'll see you guys there

Which amino acid is least likely to alter protein shape/function if substituted with an Arg residue?

• A. Lys
• B. Tyr
• C. Asn
• D. Ala

Patients with sickle-cell anemia disease have a point mutation leading to a single amino acid substitution in the hemoglobin protein, causing it to alter its shape/function. Which amino acid substitution most likely causes the disease?

• A. Ser to Thr
• B. Arg to Lys
• C. Val to Leu
• D. Glu to Val