This is the subsequent post to Part 1. In this post I’m going to talk a little bit about a slightly more zoomed out version of what was talked about in Part 1.
As you you know, keratin creates “curls” or an α-helix. In hair and fibers, these helixes line up together into a superhelix. Whenthose α-helixes join together, they form something called protofibrils (or coiled coil of two α-helices). Then a few protofibrils make microfibril (protofilament). Then it makes a macrofibril (filament).
The protofibrils are held together by four types of interactions. Those four types of bonds are: (1) Hydrogen bonding, (2) Ionic bonding, (3) Hydrophobic interactions, and (4) disulfide bonding. The disulfide bonding is the only covalent bond out of the four. It’s what keeps fibers together and influeces the curliness of a fiber. And the stretchiness of fibers is caused when the hydrogen bonds are broken. When you release your pull on the fibers, the hydrogen bonds reform, which go back to its original shape.
This is an idea of what the bonds look like. Obviously my drawings on a computer aren’t amazing, and these aren’t exactly where their positions would be.
I bet you’re probably wondering how dyes work into all of this. That will come in the next post.