Lecture on Protein Folding and Structure

Introduction

• Folding is a challenge in both everyday tasks and biology.
• In biology, folding is crucial for protein function.

Importance of Shape in Biology

• Shape and function are interlinked.
  • Protein receptors and signal molecules fit perfectly to start cellular responses.
  • Enzymes have specific shapes for substrates.

Protein Structure Levels

Primary Structure

• Sequence of amino acids in a protein.
• Amino acids are linked by peptide bonds.
• Sequence determined by genes (DNA).
• Even a single change in amino acid can affect function (e.g., sickle cell disease).
• Amino acids have carboxyl group, amino group, and R group (side chain).

Secondary Structure

• Folding begins at this level.
• Common folding types: alpha helix and beta pleated sheet.
• Hydrogen bonds between amino acid backbones play a major role.

Tertiary Structure

• Further 3D folding occurs forming a functional protein.
• Influenced by R groups:
  • R groups vary, affecting amino acid behavior.
  • Hydrophilic R groups often on the outside, hydrophobic inside.
• Structure influenced by multiple interactions:
  • Ionic bonds, van der Waals interactions, disulfide bonds, hydrogen bonds.

Quaternary Structure

• Proteins can have multiple polypeptide chains (subunits).
• Interactions like hydrogen bonds and disulfide bonds hold subunits together.

Protein Folding Mechanism

• Folding involves various interactions based on amino acid sequences.
• Complexity in folding may involve intermediate steps.
• Protein Folding Problem: an area of scientific research.
• Chaperonins (barrel-shaped proteins) assist in folding:
  • Create an ideal environment for proper folding.

Importance of Proper Folding

• Correct folding is essential for protein function.
• Misfolding linked to diseases.
• Proteins require specific environments (temperature, pH) to function.

Denaturation

• Exposure to non-ideal conditions (e.g., high heat) can denature proteins.
• Denaturation disrupts shape and function.
• Denaturation can sometimes be reversible, but often is not.

Conclusion

• Protein folding and structure are crucial for biological functions.
• Understanding folding helps with comprehending related diseases.
• Environment plays a crucial role in protein functionality.

Stay curious! - Amoeba Sisters