Chemistry of Proteins

Proteins are complex macromolecules composed of amino acids linked by peptide bonds. They are essential biomolecules involved in various structural, enzymatic, transport, and regulatory functions in living organisms. Proteins exhibit diverse structures and properties, making them crucial for biological systems.

Chemical Composition of Proteins

Proteins are primarily composed of the elements:

• Carbon (C)

• Hydrogen (H)

• Oxygen (O)

• Nitrogen (N)

• Sulfur (S) (in some amino acids like cysteine and methionine)

Basic Structure of Proteins

1. Amino Acids: Proteins are polymers of amino acids linked by peptide bonds.

2. Peptide Bonds: These are covalent bonds formed between the carboxyl (-COOH) group of one amino acid and the amino (-NH₂) group of another amino acid.

3. Levels of Protein Structure:

   • Primary Structure: Linear sequence of amino acids.

   • Secondary Structure: Alpha-helix and beta-sheet structures stabilized by hydrogen bonds.

   • Tertiary Structure: Three-dimensional folding of a single polypeptide chain.

   • Quaternary Structure: Association of multiple polypeptide chains.