So now that we know the basics of a Rama Condron plot, we're going to talk about a typical Rama Condron plots. So it turns out that there are two amino acids with a typical Rama Condron plots, and those are glistening and pro lean. And so by a typical what we really mean is that they have very unique Rama Condron plots. And so the other 18 amino acids all have Rama Condron plots that are very similar. And so they're Rama. Condom plots look like the ones that we saw in our previous lesson, but glisten and pro lean. They have really unique Rama Condron plots that stand out from all the other 18 and so well. First talk about glistens Ramachandran plot, and then we'll talk about pro leans. Ramachandran plot in a different video, so glistens. Ramachandran plot is a typical because Glisten has a very, very small our group. In fact, it's the smallest, our group of them all, and it's Our group is so small that it really does not limit the fi and side bond rotations at all. And so there's very little Starik hindrance that's encountered by glistens our group and so in our example below, we're gonna fill in our the our group of glazing and talk about its Rama Condron plot and so recall that glistens three letter code is just g l y. And it's one letter code is just g and again glistens. Our group is the smallest of them all. It's literally a single hydrogen atom and so it's so small that it really doesn't encounter any stare hindrance at all. And so recall that from our previous lesson that the white regions in a Rama Condron plot are the non permissible angles and they're non permissible because of stare Kendrick's. And in our previous Ramachandran plot, if you remember, the right side of the Rama Condron plot was pretty much all non permissible. It was pretty much all white except for tiny, tiny regions. But with glistens Ramachandran plot notice that it has, uh, permissible bond angles and pretty much every single quadrant the left quadrant upper left bottom left, upper right bottom right, Doesn't matter glistens Ramachandran plot can take on permissible bond angles and pretty much every single quadrant which is very, very unique. And so, um, glazing is really the Onley amino acid that has this ability because it's the only amino acid that has such a small, our group that encounters very, very little Starik hindrance. And and so this is gonna be a key feature of glazing and will be ableto refer back to this on some of our different topics later throughout our course. So it's important to keep this in mind that glistens. Our group gives it this special feature of taking on different bond angles that other amino acids can't take on, and it can fit into small spaces that other amino acids can't fit in. So, uh, this concludes our lesson on the atypical Ramachandran plot of glazing and we'll get some practice and then we'll talk about the atypical Ramachandran plot of pulling, so I'll see you guys in those videos.
Why does Gly have a uniquely interesting Ramachandran plot in comparison to the other α-amino acids?
Its small R-group restricts the φ and ψ bond rotations via noncovalent interactions.
Glycine’s R-group forms strong hydrogen bonds that greatly frees its bond rotations.
Gly’s R-group avoids steric hindrance & expands regions of energetically permissible φ and ψ bond angles.
b and c.
Atypical Ramachandran Plots
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So now that we've talked about glistens, unique Rama Condron plot, let's talk about pro leans Ramachandran plot, which is also unique and so pro leans. Ramachandran plot is unique because pro Lien has a bulky cyclic our group, and it's bulky, cyclic. Our group really does greatly restrict or limit the fi and side bond rotations. And so, in our example below will be able to fill in the our group of pro lean recall some of its abbreviations, and we'll talk about pro leans Ramachandran plot and so recall that pro Leans three letter code is just P R. O. And it's one letter code is just a P. And just like a p pro leans, our group really does resemble the loop of api. And so, just like a P has a backbone. So does prowling Soap. Rolling has this amino acid backbone And then, just like trolling the P has a loop just like this pro leans. Our group really does look like the loop of a flip Pete. And so, uh, that can help you remind remind you of its structure. And then also you can think of pro lean Pentagon, so they both start with peas and that can help you remind you that really, it's our group is going to form like a Pentagon type shape. So it's gonna have these points over here that need to be connected. And so really, these points are all going to be methylene groups or CH two groups. And so really, it's just gonna be ch two c h two ch two and then it connects back to the nitrogen. And again, which will see, is because it connects back to the nitrogen here that, uh, the amino group of polling has one less hydrogen than all of the other amino acids. So something important to keep in mind as we move forward. So notice that glistens. Our group is really bulky and cyclic. And so there's a lot of stare Kendrick's encountered in there, and that ends up restricting both the fi and the sai bond angles that we see here. And so when we take a look at glistens Rahman Khan reply again on the X axis, we have the five bond angles and on the side of the Roman Condra plot, we have the side bond angles and so which will see, is that, uh, there's really Onley, one region that has permissible bond angles in it. And remember that the darker the region is, the more permissible it is. The light regions represent less permissible. So there is a little bit that of permissibility that extends into the bottom left quadrant here. But there's not much at all. And there's definitely no dark shaded regions in the bottom left. And that's something that's very different from all of the other amino acids, because all the other amino acids really have dark shaded regions, uh, down in this quadrant as well. But that's lacking, and pro leans around the contra plot, and you'll also notice that there's nothing. There's no permissible regions on the right half of the Rama Condron plot, and so this is really, really restricted, and it's something that's very unique and interesting to keep in mind. And so, hopefully, by comparing glistens, Ramachandran plot So pro leans Ramachandran plot you'll get a better understanding of what a Rama condom plot is really trying to show you. And so with again with glistens Ramachandran plot, it's Our group is so small that it does not limit find side bond angles and by not restricting those fine side bond angles it takes on regions and all four quadrants. That's glazing but with pro Lean, on the other hand, is pretty much the complete opposite. It's bulky, cyclic. Our group restricts those fi inside bond angles, really to just one quadrant in the upper left, and there is a little bit in the bottom left. But not a lot, then no dark regions. So again, hopefully this help your understanding of Rama Condron plots, and I'll see you guys in the practice video.
The Ramachandran plot of Leu most likely resembles which of the following plots?