00:01
Okay, so in this question, we're given a few different functional groups and we're asked to determine not only where they come from, but also the type of interaction they can form.
00:07
All right, so the first one, notice that both of these things are the same, and they both come from cysteine.
00:14
So this is cysteine plus cysteine.
00:17
So the types of interactions they can form, and this is why cysteine is so interesting biochemically, is they can actually form covalent bonds called disulfide bridges.
00:26
So disulfide bridge is.
00:35
All right.
00:36
And those are actually very important to the structure of a lot of proteins.
00:39
All right.
00:39
So next we, for part b, we've got what looks like four carbons followed by a namine.
00:46
So that's going to be lysine.
00:48
With the second one, it's just going to be single carbon and then a carbaclyic acid group.
00:56
So that's going to be aspirate or aspartic acid.
01:02
So there are two main interactions that can go on here.
01:07
Notice that the lysine is protonated and the aspartic acid is deprotonated.
01:12
So obviously there can be acid interaction here where you have proton transfer.
01:18
But you can also have hydrogen bonding up here.
01:22
And the reason is that both nitrogen and oxygen are hydrogen bond.
01:29
Either donators or acceptors.
01:33
So either way, these things are going to interact relatively strongly.
01:39
So for c, we again have something that looks pretty similar to the second half of part b, and that's because they are similar...