Alpha-keratin

[2] α-keratin is a polypeptide chain, typically high in alanine, leucine, arginine, and cysteine, that forms a right-handed α-helix.

The different types, alignments, and matrices of these IFs account for the large variation in α-keratin structures found in mammals.

There, the alpha-keratin intermediate filaments will collect and form networks of structure dictated by the use of the keratin cell as the nucleus simultaneously degrades.

[10] Under high tension, alpha-keratin can even change into beta-keratin, a stronger keratin formation that has a secondary structure of beta-pleated sheets.

[11] Alpha-keratin tissues also show signs of viscoelasticity, allowing them to both be able to stretch and absorb impact to a degree, though they are not impervious to fracture.

This causes an increase in disulfide bonds that are able to stabilize the keratin structure, allowing it to resist a higher level of force before fracture.

On the other hand, soft alpha-keratins, such as ones found in the skin, contain a comparatively smaller amount of disulfide bonds, making their structure more flexible.