Protein Structure

Introduction

• Proteins are essential biomolecules that play various critical roles in living organisms.
• The structure of a protein determines its function.

1. Primary Structure

• The primary structure of a protein refers to the sequence of amino acids linked together in a specific order.
• The sequence of amino acids is determined by the gene that encodes the protein.

2. Secondary Structure

• Secondary structure refers to the local folding patterns within a protein's primary structure.
• Two common types of secondary structures are alpha helices and beta sheets.
• These structures are stabilised by hydrogen bonds between amino acids.

3. Tertiary Structure

• Tertiary structure is the overall three-dimensional shape of a protein.
• It results from the folding and interactions of secondary structures.
• Tertiary structure is crucial for a protein's function, as it determines its active sites and binding regions.

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Protein Structure

4. Quaternary Structure

• Some proteins are composed of multiple polypeptide chains.
• Quaternary structure refers to the arrangement and interaction of these individual subunits.
• Examples include haemoglobin, which consists of four subunits, and enzymes with multiple subunits working together.

5. Protein Folding

• Proper protein folding is essential for its functionality.
• Proteins fold into their functional shapes through various interactions, including hydrogen bonds, disulfide bridges, hydrophobic interactions, and van der Waals forces.

6. Denaturation

• Protein structure can be disrupted by changes in temperature, pH, or chemical agents.
• Denaturation occurs when a protein loses its native structure and, as a result, its function.

7. Protein Function

• Protein structure determines function.
• Proteins can act as enzymes, transport molecules, receptors, antibodies, and structural components in cells.
• Their diverse functions are a result of their unique structures.

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Protein Structure

Summary

Protein structure is a hierarchical organisation, starting with the primary structure (amino acid sequence) and progressing to secondary, tertiary, and quaternary structures. Proper folding is crucial for protein functionality, and denaturation can disrupt this structure. Proteins have diverse functions in cells, determined by their unique structures, and are essential for various biological processes. Understanding protein structure is fundamental in biology and biochemistry.