The Proteins of Normal and Aberrant Hair Keratins
January 1981
TLDR Hair is mostly made of three protein types: helical, high-sulfur, and high-tyrosine.
The study from 1981 examined the composition of mammalian hard keratins, which consisted of filaments about 7 nm in diameter embedded in a nonfilamentous matrix. The filaments were made of helical proteins with low cystine content, while the matrix contained two families of nonhelical proteins: one rich in cystine (high-sulfur proteins) and the other rich in glycine and tyrosine (high-tyrosine proteins). These three protein groups made up 85% or more of the hair fiber's mass, with the rest comprising intercellular membranes, cellular remnants, medulla, and cuticle.
