>>10465987What role does the hair shaft play in its overall texture? In short, protein bonding. The strands of hair that you see are comprised largely of dead cells packed full of the fibrous protein known as keratin. This protein contains many copies of the amino acid cysteine, which is special because it has a sulfur-containing chemical group that allows it to form strong bonds with other sulfur containing molecules. In the case of hair, which is largely keratin, these cysteine amino acids can bond with other cysteines further down the hair shaft contributing to curling of the hair between the bonds. Curly hair has more of these bonds, referred to as disulfide bonds, than straight hair because the follicle shape and angle allows different regions of the hair to come closer together making these bonds easier to form.
Ultimately, our follicles are the biggest determinant of our hair shape. Although we can’t control this part of our hair, understanding the science of curly hair has allowed us to overcome the features genetics gave us. Perms and relaxing treatments take advantage of keratin’s ability to disulfide bond to change the structure of our hair to the state we want. If you have curly hair but want straight hair, then you just need to use chemicals that can break up, or “relax”, these bonds. If you want to go from straight to curly, then all you need is a chemical to allow these bonds to form.
