Collagen and keratin protein

Summary

This video discusses two key fibrous proteins in the human body: collagen and keratin. Collagen, the most abundant protein, forms a triple-helix structure with glycine, proline, and hydroxyproline. Hydroxyproline is produced from ascorbic acid. Elastin, another important fibrous protein, also contains hydroxyproline and desmosine. The video emphasizes collagen's role in maintaining tissue integrity through hydrogen bonding. Keratin, an alpha-helix protein, differs from collagen with its intrachain disulfide linkages and hydrogen bonds, contributing to tissue strength and stability.

Takeaways

• 💪 Collagen is the most abundant protein in the human body, present in almost all tissues.
• 🔄 Collagen is a trimeric protein made of three peptide chains that wrap around each other, forming a triple helix (not an alpha-helix).
• 🔗 The characteristic structure of collagen is due to a repeating motif of glycine, proline, and hydroxyproline.
• 💧 Hydrogen bonding between the three peptide chains holds the collagen structure together.
• 🧪 Hydroxyproline in collagen is derived from proline via a metabolic process involving ascorbic acid (vitamin C).
• 🧬 Elastin, another fibrous protein, also contains hydroxyproline and is responsible for tissue elasticity. It includes desmosine, a derivative of lysine.
• 🚫 Collagen and elastin are insoluble proteins, contributing to their structural roles in tissues.
• 🧵 Keratin, a fibrous protein like collagen, exists in two forms: alpha-keratin and beta-keratin.
• 🌀 Alpha-keratin forms an alpha-helix structure, with hydrogen bonds and disulfide cross-links between monomers providing strength.
• 🔒 Disulfide bridges in keratin occur between different monomers, not within the same monomer, adding stability to the structure.

Q & A

What are collagen and keratin classified as?

Collagen and keratin are classified as fibrous proteins, which are important structural components in the body.

Which protein is the most abundant in the human body?

Collagen is the most abundant protein in the human body.

How is collagen structured at the molecular level?

Collagen is a trimeric protein made up of three peptide chains that wrap around each other to form a triple helix. However, this is not an alpha-helix.

What unique motif is found in collagen, and what amino acids are involved?

The unique motif in collagen consists of a repeating sequence of glycine, proline, and hydroxyproline.

What is the role of hydroxyproline in collagen, and how is it produced?

Hydroxyproline helps stabilize the collagen structure. It is produced from proline through a metabolic process that requires ascorbic acid (vitamin C) as a precursor.

What is elastin, and how is it related to collagen?

Elastin is another fibrous protein found in tissues, helping them remain elastic. It contains hydroxyproline like collagen and has a unique component called desmosine, which is derived from lysine.

What is the structural difference between collagen and keratin?

Collagen forms a triple helix that is not an alpha-helix, while alpha-keratin forms an alpha-helix. Keratin is a multimeric protein, meaning two peptide chains wrap around each other.

What type of bonding stabilizes collagen's structure?

Hydrogen bonding between the three peptide chains helps stabilize collagen's structure.

What type of bonding stabilizes keratin's structure?

Keratin's structure is stabilized by hydrogen bonding and intrachain disulfide cross-links between two monomers.

Why are fibrous proteins like collagen and keratin important in the body?

Fibrous proteins like collagen and keratin provide structural support and strength to tissues, allowing them to withstand tension and maintain stability.