Keratin holds incredible significance in our daily lives without us even realizing it. It is the protein that constitutes our hair, nails, and skin. Keratin is also found in feathers, hooves, horns, and wool. It is one of the toughest proteins because of its unique and intricate structure, which makes it resistant to physical and chemical damage. But, have you ever wondered what amino acids make up keratin? Let's dive into the world of keratin and understand the amino acids that form its building block.

Keratin is composed of 18 amino acids, which form a polypeptide chain. These amino acids differ in terms of their size, shape, and charge, which gives keratin its unique characteristics. The five most abundant amino acids present in keratin are glycine, alanine, serine, valine, and cysteine.

• Glycine is the smallest amino acid and is present in between the other amino acids to maintain the flexibility of the keratin structure.
• Alanine is similar to glycine, and its unique characteristic is its hydrophobicity.
• Serine is a polar amino acid that forms hydrogen bonds within the keratin structure.
• Valine is unique because it has a branched side chain that helps to form hydrophobic interactions.
• Cysteine is present in keratin in relatively small amounts, but it is critical as it forms cross-links with other cysteine residues to form the disulfide bond, which is responsible for the toughness and resilience of keratin.

Aside from the five most abundant amino acids, keratin also contains other amino acids such as lysine, arginine, and tyrosine. Lysine and arginine play a significant role in the formation of hydrogen bonds that create the alpha helix structure of keratin. Tyrosine, on the other hand, plays a significant role in the UV absorption properties of keratin, making it photo-protective.

It's also essential to note that the sequence and arrangement of amino acids in keratin differ according to the type of tissue it constitutes. For instance, the amino acid composition of hair keratin is different from that of nail keratin, and the composition of wool keratin is different from that of feather keratin. This difference in amino acid arrangement makes keratin have tissue-specific properties.

In conclusion, keratin is an intricate protein that comprises amino acids that play an essential role in its unique features. These amino acids differ in size, shape, and charge, which contribute to keratin's rigidity, flexibility, and resistance to damage. The formation and sequence of amino acids greatly influence keratin's properties, making it different in various tissues.

Learning about the amino acids present in keratin will enable us to appreciate the importance of this protein in our daily lives and the animal kingdom.