And because it's minimally invasive, because of that tiny H atom, it can fit into either hydrophobic or hydrophilic environments. And finally, let's take a look at another special case known as proline. Now, proline is technically a hydrophobic side chain, but because of its special structure of that side chain, we label it as a special side chain. So what's so special about the proline? Well, if we examine our side chain, this is the only side chain that connects not only to the alpha carbon, but also to that nitrogen. And we form this five membered ring.