Keratin belongs to a family of fibrous structural proteins. This particular type of protein works to shield the epithelial cells from any kind of stress or damage. Moreover, keratin is the most important structural substance that comprises the external stratum of the human skin.
The monomers of keratin accumulate to form bundles that make up the intermediate filaments. These filaments are not only sturdy, but also comprise brawny epidermal appendages that are not mineralized. They are usually found in amphibians, birds, mammals and reptiles. Aside from keratinized tissues, chitin is the only known biological substance that is somewhat close to this protein in strength and toughness.
In fact, keratin is a highly potent protein, which is the foremost constituent of the human skin, nails, hairs and teeth. In the case of animals, keratin also comprises their horns and hooves. The skin, hair, nails, teeth, hooves and horns are formed when keratin combines with amino acids, which possess many exceptional properties. Subject to the intensity of the different amino acids, keratin can also be hard and inflexible, such as the horns and hooves. On the other hand, keratin can also be soft as in skin. Our body sheds dead cells when new cells come to the fore from beneath. In case the dead cells remain in a good state, even they work as an external layer that protects the new and delicate tissues below them by serving as an insulator.
Keratin does not dissolve easily, as it encloses the compound cysteine disulfide. In other words, keratin possesses the ability to shape disulfide bridges, which form a helix shape. This helix shape is very strong, because the sulfur atoms bond with one another, thereby producing a fiber-like matrix that does not dissolve readily. Subject to the amount of cysteine disulfide contained by keratin, such bonds are usually very strong that makes the cells present in the hooves extremely hard. Alternatively, these bonds can also make the tissues of the skin and hair soft as well as flexible. Keratin releases a smell akin to sulfur as this protein contains cysteine disulfide in elevated levels. This is the reason why keratin is burnt, many people loathe the smell.
Keratin is developed by keratinocytes, which are living cells that comprise a major part of our skin, nails, hair as well as other body areas. These cells push their way upwards gradually and finally die to form a protective layer on the outer epidermis. Our body sheds several thousand keratinocytes daily and often the process of shedding these cells is accelerated due to a variety of medical conditions, including psoriasis.
When the outer keratin layer is damaged, it may lead to flaking or an unhealthy looking skin, nails and hair.
Human hair as well as nails have a tendency to become dehydrated and, therefore, brittle. This is because dead keratin is continuously being pushed upwards. When you consume foods such as gelatin, which helps to ensure that the skin and nails remain moist, they continue growing healthily and eventually grow out. Generally speaking, the thicker the keratin layer is your hair and nails will remain healthier. This is mainly because the dead cells on the exterior help to protect the living cells beneath them. In addition, when you keep the external keratin layer moist, it will also help the skin and nails to remain healthy and not allow them to split or crack easily. This is irrespective whether it is the human skin or a horse's hooves.
Keratin is of two types. The first type is called alpha-keratin, which is present in profuse amounts in humans as well as animals. The second type of keratin is called beta-keratin, which is mainly found in birds and reptiles. Beta-keratin is responsible for making the skin of reptiles more rigid compared to the skin of mammals that contain alpha-keratin.
Aside from making the skin tough and strong, keratin also forms an important element of the hair. It helps the hair to become stronger, thereby making it not easily breakable. It is also helpful for smooth and coat frizzy hair shafts that are frayed. Keratin also helps to mend damaged hair, as it works to make the hair shafts smooth and coats them enabling them to retain moisture. At the same time, keratin is useful in preserving the firmness and elasticity of the skin. It also regulates cell growth as well as renewal, thereby helping to control wrinkles and making them smooth.
Keratin affects melanin and also influences skin pigmentation. This vital protein has an important role in making the skin waterproof. In addition, keratin also creates a barrier that prevents bacteria as well as other micro-organisms from penetrating the skin easily.
Keratin also makes up our nails. As a result, the skin is less vulnerable to breaking and chipping. This protein also forms the main part of different hardened structures in animals, like beaks, horns and also feathers.