What is the Difference Between Keratin and Carotene

The main difference between keratin and carotene is that keratin is a fibrous protein mainly composed of amino acids, including cysteine, serine, and glycine, whereas carotene is a group of organic compounds known as carotenoids.

Keratin and carotene are both organic compounds that play important roles in biological systems. But they differ in their chemical compositions and functions.

Key Areas Covered

1. What is Keratin 
     – Definition, Features, Importance
2. What is Carotene
     – Definition, Features, Importance
3. Similarities Between Keratin and Carotene
     – Outline of Common Features
4. Difference Between Keratin and Carotene
     – Comparison of Key Differences

Key Terms

Carotene, Keratin, Alpha Keratin, Beta Keratin

What is Keratin

Keratin is mainly composed of amino acids, which are organic compounds that form proteins. The most abundant amino acids in keratin include cysteine, serine, and glycine. The unique arrangement of these amino acids gives keratin its exceptional properties. Cysteine plays a critical role in keratin’s structure as it contains a sulfur atom that forms disulfide bonds with other cysteine residues, creating cross-links that contribute to the protein’s strength and stability.

There are two main types of keratin; alpha keratin and beta keratin. The alpha keratin and beta keratin are present in different organisms. The alpha keratin is mainly present in mammals, including humans. It is responsible for the formation of hair, nails, fur, wool, and the outermost layer of the skin. The hierarchical structure of alpha keratin includes intermediate filaments that bundle together to form microfibrils, which further assemble into microfibrils, resulting in the formation of larger fibers.

Meanwhile, beta keratin is mainly found in reptiles, birds, and certain amphibians. It forms the basis for the production of scales, feathers, beaks, claws, and other protective coverings. Beta keratin has a similar hierarchical structure to alpha keratin but with some structural differences, allowing it to withstand the unique mechanical demands of reptilian and avian structures.

Functions of Keratin

There are many functions of keratin. Keratin provides strength, rigidity, and resilience to the structures it forms. In mammals, keratin in the hair shaft gives it tensile strength and flexibility, allowing it to withstand mechanical stress. Likewise, keratin in nails provides a protective shield for the fingertips.

Keratin also acts as a barrier against external environmental factors. In the outermost layer of the skin, known as the epidermis, keratin forms a waterproof and protective barrier that prevents dehydration and protects against harmful substances and pathogens. In certain organisms, such as birds, keratin-rich structures like feathers contribute to thermoregulation. Feathers provide insulation, trapping air and maintaining body temperature.

What is Carotene

Carotene is a group of organic compounds known as carotenoids. Carotene is a hydrocarbon compound composed of carbon and hydrogen atoms. The most well-known abundant carotenoid is beta carotene, which gives fruits and vegetables their characteristic orange, red, and yellow colors. Beta carotene is classified as a provitamin A carotenoid because it can be converted into vitamin A within the body. Other common carotenoids include alpha-carotene, lycopene, lutein, and zeaxanthin, each with its unique chemical structure and properties.

Carotene, mainly beta-carotene, acts as a potent antioxidant in the body. Antioxidants help to neutralize harmful free radicals, unstable molecules that can cause oxidative stresses and damage cells. By scavenging free radicals, carotene helps protect against chronic diseases such as cardiovascular diseases, certain cancers, and age-related macular degeneration.

Beta carotene, as a provitamin A carotenoid, is important in the production of vitamin A. Once ingested, beta-carotene is converted into vitamin A  in the liver and intestines. Vitamin A is essential for maintaining healthy vision, promoting growth and development, supporting the immune system, and contributing to various physiological processes. Carotenoids such as lutein and zeaxanthin accumulate in the macula of the eye, where they help filter blue light and protect against oxidative damage.

Carotene-rich foods can contribute to healthy skin. Beta carotene is involved in maintaining skin integrity and promoting a youthful appearance. It helps protect the skin against UV-induced damage, improves skin hydration, and may even aid in wound healing.

Similarities Between Keratin and Carotene

• Keratin and carotene are organic compounds.
• Both keratin and carotene are naturally occurring substances found in various organisms.
• They have important biological roles.

Difference Between Keratin and Carotene

 Definition

Keratin is a fibrous protein mainly composed of amino acids, including cysteine, serine, and glycine, whereas carotene is a group of organic compounds known as carotenoids.

Functions

Keratin provides structural support, strength, and protection to tissues, while carotene functions as a pigment and a precursor to vitamin A.

Sources

While keratin is found abundantly in animal tissues, carotene is commonly found in fruits and vegetables.

Conclusion

Keratin and carotene are both organic compounds that play important roles in biological systems. But they differ in their chemical compositions and functions. The main difference between keratin and carotene is that keratin is a fibrous protein mainly composed of amino acids, including cysteine, serine, and glycine, whereas carotene is a group of organic compounds known as carotenoids.

Reference:

1. “Keratin.” Britannica Encyclopedia.
2. “Carotene – Overview.” Science Direct.

Image Courtesy:

1. “KeratinF9” (CC BY-SA 3.0) via Commons Wikimedia
2. “Alpha-carotene” (CC BY-SA 3.0) via Commons Wikimedia