What is the natural form of keratin?

Keratin naturally exists in two primary forms: α-keratin and β-keratin.

Understanding Keratin's Two Forms

Keratin, a fibrous structural protein, is a key component of various biological structures. It's not a single entity but rather a family of proteins. These proteins are typically categorized into two main forms based on their structure and location:

α-keratin

• Location: This form of keratin is predominantly found in softer tissues. Examples include:

  • Skin: The outer layers of human skin contain α-keratin, providing a protective barrier.
  • Hair: Human hair is primarily composed of α-keratin, giving it strength and flexibility.
  • Sheep Wool: Similar to human hair, sheep wool is also a rich source of α-keratin.

• Properties: α-keratin is characterized by its helical structure, often described as a coiled coil. This structure gives it a certain degree of flexibility and elasticity, suitable for its presence in soft tissues.

β-keratin

• Location: In contrast to α-keratin, β-keratin is generally found in harder structures such as:

  • Horns: The tough exterior of horns is made up of β-keratin.
  • Feathers: The rigid structures of bird feathers rely on β-keratin for their form and strength.
  • Claws: Claws in animals, whether on birds or mammals, are made up of this type of keratin.
  • Hooves: The hard outer layer of hooves also contains β-keratin.

• Properties: β-keratin is characterized by its sheet-like structure, known as a beta-pleated sheet. This structure provides high tensile strength and rigidity, making it suitable for the construction of hard tissues.

Key Differences Summarized

Conclusion

Both α-keratin and β-keratin are essential, albeit different, forms of the protein, serving diverse functions across various species and tissues.