Protein Structure and Primary/Secondary Structure

Protein Structure

Primary Structure

• Sequence of amino acids in a polypeptide chain
• Determined by the sequence of nucleotides in the gene that encodes the protein
• Primary structure determines the overall properties of a protein

Secondary Structure

• Local arrangements of amino acids that are stabilized by hydrogen bonds
• Alpha helices (α-helices) and beta sheets (β-sheets) are common secondary structures
  • Alpha helices: spiral shape, hydrogen bonds between every 4th amino acid
  • Beta sheets: flat, extended, hydrogen bonds between amino acids in parallel or antiparallel chains

Tertiary Structure

• 3D arrangement of amino acids in a polypeptide chain
• Determined by interactions between side chains (R groups) and the backbone
• Hydrophobic interactions, ionic interactions, and disulfide bonds contribute to tertiary structure

Quaternary Structure

• Arrangement of multiple polypeptide chains (subunits) in a protein
• Subunits are held together by non-covalent interactions (hydrogen bonds, ionic interactions, etc.)
• Quaternary structure is important for protein function and stability

Protein Folding

• Process by which a polypeptide chain assumes its native 3D structure
• Influenced by factors such as temperature, pH, and the presence of chaperone proteins
• Misfolded proteins can lead to diseases such as Alzheimer's and cancer

Denaturation

• Loss of native structure and function due to external factors (heat, pH, chemicals, etc.)
• Can be reversible or irreversible, depending on the severity of denaturation
• Denaturation can lead to protein aggregation and precipitation

Protein Structure

• A protein's primary structure is the sequence of amino acids in a polypeptide chain, determined by the sequence of nucleotides in the gene that encodes the protein.
• Primary structure determines the overall properties of a protein.

Secondary Structure

• Local arrangements of amino acids are stabilized by hydrogen bonds, forming alpha helices (α-helices) and beta sheets (β-sheets).
• Alpha helices: spiral shape, hydrogen bonds between every 4th amino acid.
• Beta sheets: flat, extended, hydrogen bonds between amino acids in parallel or antiparallel chains.

Tertiary Structure

• The 3D arrangement of amino acids in a polypeptide chain is determined by interactions between side chains (R groups) and the backbone.
• Hydrophobic interactions, ionic interactions, and disulfide bonds contribute to tertiary structure.

Quaternary Structure

• The arrangement of multiple polypeptide chains (subunits) in a protein is held together by non-covalent interactions (hydrogen bonds, ionic interactions, etc.).
• Quaternary structure is important for protein function and stability.

Protein Folding

• Protein folding is the process by which a polypeptide chain assumes its native 3D structure.
• Factors influencing protein folding include temperature, pH, and the presence of chaperone proteins.
• Misfolded proteins can lead to diseases such as Alzheimer's and cancer.

Denaturation

• Denaturation is the loss of native structure and function due to external factors (heat, pH, chemicals, etc.).
• Denaturation can be reversible or irreversible, depending on the severity of denaturation.
• Denaturation can lead to protein aggregation and precipitation.