Navigation Links
Keratin


Microscopic view of stained keratin.

Keratin is a protein used by numerous groups of animals as a structural element, and is a classic example of a fibrous protein.

Keratin is a tough, insoluble protein found in the outer layer of the skin of human beings and many other animals. This outer layer of skin is called the epidermis. The outermost layer of cells of the epidermis contains keratin. The keratin in these cells makes the skin tough and almost completely waterproof. In places where the skin is exposed to much rubbing and pressure such as parts of the hands and feet the number of cells containing keratin increases and a callus develops. Cells that contain keratin are constantly being shed and replaced by new ones. The condition known as dandruff results when the scalp sheds such cells.

Keratin molecules are helical and fibrous, twisting around each other to form strands called intermediate filaments. These proteins contain a high percentage of sulfur-containing amino acids, largely cysteine, which form disulfide bridges between the individual molecules, resulting in a fairly rigid structure. Human hair is approximately 14% cysteine.

There are two main forms of keratin, alpha-keratin and beta-keratin. Alpha-keratin is seen in humans and other mammals, beta-keratin is present in birds and reptiles. Beta-keratin is harder than alpha-keratin. Structurally alpha-keratin have alpha-helical coiled coil structure while beta-keratin have twisted beta sheet structure.

In humans, the keratin family of proteins is divided into the soft epithelial keratins or cytokeratins and the hard hair keratins. These can be divided into type I (acidic) and type II (basic to neutral) subfamilies. Keratin is also what fungi that infect us (such as Athlete's Foot and Ringworm) feed on.

Keratin is also a part of certain structures that grow from the skin. The nails and hair of human beings contain keratin. It can be thought of as nature's all-purpose plastic, forming such various growths as horns, hoofs, claws, beaks, feathers and scales, all of which consist mainly of keratin. It helps make these structures stronger and better-suited to protect the body from the environment.

See also

References

  • World Book Encyclopedia (1998)

External links


'"/>


(Date:4/5/2017)... Allen Institute for Cell Science today announces the launch ... dynamic digital window into the human cell. The website ... deep learning to create predictive models of cell organization, ... suite of powerful tools. The Allen Cell Explorer will ... resources created and shared by the Allen Institute for ...
(Date:3/30/2017)... 30, 2017  On April 6-7, 2017, Sequencing.com will ... hackathon at Microsoft,s headquarters in ... focus on developing health and wellness apps that provide ... the Genome is the first hackathon for personal ... largest companies in the genomics, tech and health industries ...
(Date:3/27/2017)... N.Y. , March 27, 2017  Catholic ... Information and Management Systems Society (HIMSS) Analytics for ... EMR Adoption Model sm . In addition, CHS ... of U.S. hospitals using an electronic medical record ... for its high level of EMR usage in ...
Breaking Biology News(10 mins):
Other biology definition