Chymotrypsin

in this video, we're going to briefly talk about the significance of protein breakdown as we review the pep today's Kimo trips. And so protein breakdown is actually critical toe living systems for many different reasons, including the following two reasons. The first is that proteins and enzymes that are no longer needed inside of the cell can be degraded through protein breakdown so that their amino acids can be recycled and used to build other proteins and enzymes that are needed now. The second reason for why protein breakdown so critical the living systems is that proteins that air ingested through the diet actually need to be broken down in order to be absorbed by our intestines and used by ourselves. Now recall from our previous lesson videos that pep today is just the specific class of enzymes that catalyze is protein breakdown. And, of course, the specific enzyme Kimo trips in is a unexamined of a pep today. So it is a digestive hydro, lies or a pep today's enzyme that breaks that breaks down proteins and recall from our previous listen videos that chemo trips and actually has a preference for which amino acid residues it recognizes for cleavage. And so it always cleaves the C terminal end aunt. It typically has a preference for these aromatic amino acid residues, which are final Allan E tire scene and tripped a fan. And then it also has a lowered preference for blue scene and meth Einen, however moving forward were mainly going to be focusing on the aromatic amino acid residue preference for chemo trips in now as well. See down below, Kimo trips in is going to be secreted by the pancreas in response to eating a meal. And so, if we take a look down below at our example image over here on the left notice we have this human guy who, if we zoom in on his digestive system right here, we can see that we have his stomach right here and inside of his stomach. We've got some broccoli for those of you that are vegetarians out there. And broccoli is a vegetable that is quite high in protein. And so as this broccoli makes its way through the digestive system, which will notice is that we have an organ here called the pancreas that's responsible for ultimate lease accreting Kimo trips. And so recall that Kimo trips and actually has a Zim again that's referred to as Kimo Trip Synergen. And so, originally, the cells of the pancreas will secrete Kimo trip Synergen in its Z Imogen form, which recalls the inactive form and then chemo trip Synergen through cleavage here. Which is why we have the scissors. Um, it can be activated into chemo trips and then chemo trips and can finally begin to degrade. Um, the proteins of the broccoli that we ingested through eating a meal through the diet. And so notice over here on the right. We're showing you a specific peptide right here and notice that we're showing you that there are specific cleavage points here when we treat this peptide with Kimo trips and and so recall that it recognizes aromatic amino acid residue. So notice right here in the blue background. We have fennel, Alan. I mean, that's being recognized. And of course, the C terminal end is what gets cleaved. So over here we have the C terminal end. And so that's why this peptide bond is being cleaved. And then we also have tyrosine here, and tyrosine is another aromatic amino acid residue. So the C terminal peptide bond also gets cleaved. So on the left, what we have is just one peptide fragment. But after the two cleavages, we end up getting three separate peptide fragments that are color coded here. So we get this blue fragment right here, this green fragment here. And then we have the purple fragment over here on the far right. And so, really, this is just a reminder in a review of chemo trips and activity. And so in our next video, we'll be able to talk specifically about Kimo trip sins Active site. So I'll see you guys in that video.

so kinda trips is actually one of the best studied enzymes that uses Michaelis mention kinetics and multiple catalysis mechanisms, which makes comma trips in a perfect opportunity for us to be able to apply a lot of the older concepts that we talked about in our previous lesson videos. And so in this video, we're going to talk about chemo trip sins, active site and so chemo trip sins Active site will stabilize the transition state just like all other enzymes do. But it's specifically stabilizes the transition state using both co violent and general acid based Catala sis. And we'll talk more about this idea right here later in our course when we're talking about chemo trips and specific catalytic mechanism. But for now, all I really want you guys to note is that Kim, a Trip sins active site, contains three specific amino acid residues that are together referred to as the catalytic Triad and tries a prefix that means three, which is referring to these three amino acid residues and the three amino acid residues are Asper Tate 102 History in Searing 1 95 and all three of these amino acid residues are in chemo trip since active site. In all, three of them are absolutely required for chemo trip since Catala. Sis, If we remove any one of these three amino acids, then Kimo trip sins. Catalysis is not going to work. And so note that these numbers right here after the amino acids air, just referring to the specific position that they come in chemo trip sins, primary sequence. And so I would not focus on memorizing these specific numbers. I would more so focus on memorizing the amino acids themselves. Asper, Tate, history and Syrian. And so notice down below in our image here we're showing you combo trips and active site in this yellow structure represents kinda trips interactive site. And we can see the catalytic triad in kinda trip since active site, which is again Asper Tate 102 History in searing 1 95. Now down below. These two bullet points were telling you exactly why these three amino acids are required for chemo trips and Scott Alice and we're going to start off with history in 57 which is right here in the middle. So history in 57 will actually hydrogen bond with both of its neighbors. It will hydrogen bond with Syrian 1 95 and Asper Tate 102 And so we can see here that this history and 57 will hydrogen bond with the Syrian, and it will also hydrogen bond with the Asper Tate. And so all of this hydrogen bonding that history and 57 is doing is really just establishing searing 1 95 as a stronger nuclear five. And ultimately, what we'll see is that this hydrogen right here on the Syrian is gonna be transferred over to the history. So the history is going to act as a base and take up this hydrogen. And that's exactly what we see over here that the hydrogen is being picked up by the histamine, giving it a additional positive charge here and ultimately establishing the searing with a negative charge, making it a stronger nuclear foul. And so what you might be wondering is, why in the world is Asper Tate 102 needed for histamine to acquire this hydrogen? Well, the reason that Asper Tate 102 is required is because, uh, this hydrogen bond with Asper Tate 102 will actually position history in 57 toe Act as a better overall base to acquire this particular hydrogen. So if we were to remove this Asper Tate residue, then histamines Pekka here would actually not be suitable to acquire this hydrogen. And so, uh, the Asper Tate 102 is specifically there to position history in to be a better base. And without the aspect 812 history would not be able to acquire this hydrogen and make the Syrian a strong nuclear file. And so all of these interactions are all dedicated to making Syrian a strong nuclear file. So what we can say is that aspect 8102 and history in 57 are both going to enhance the nuclear Filic ability of searing 1 establishing it as a stronger nuclear file. And so this nuclear file right here is going to be what we start off with when we talk about Kim, a trip sins catalytic mechanism later in our course. But for now, this concludes our introduction to chemo trip sins active site and we'll be able to apply the concepts that we've learned in our next few videos. So I'll see you guys there

Which amino acids in chymotrypsin's active site are critical participants in the cleavage of the substrate?

• A. His, Ser, Asn.
• B. His, Ser, Asp.
• C. His, Ser.
• D. Asp, Lys.

The following polypeptide N-G-I-F-D-A-Y-G-N-T-W-R-A-P-C-F-V-A is cleaved by chymotrypsin to produce multiple peptide fragments. Based on the specificity of chymotrypsin cleavage, how many peptide fragments are produced?

• A. 2 peptide fragments.
• B. 3 peptides fragments.
• C. 4 peptide fragments.
• D. 5 peptide fragments.
• E. 6 peptide fragments.
• F. No cleavage event occurs

The activity of chymotrypsin drastically changes as the pH fluctuates in the relatively small range of pH 5-9. What amino acid residue in chymotrypsin's active site is most likely to be responsible for this effect of pH?

• A. Asp-102.
• B. His-157.
• C. Ser-195.
• D. Tyr-23.
• E. Cys-198.
• F. Asn-122.