Protein Structure Quiz

Protein Structure

• Globular proteins have a spherical shape and are usually soluble in water, with examples being insulin and albumins.

Levels of Protein Structure

• There are four levels of protein structure: primary, secondary, tertiary, and quaternary, with each level being more complex than the previous one.

Primary Structure

• The primary structure of a protein refers to the specific sequence of amino acids in a polypeptide chain.
• A protein can have one or more polypeptide chains.
• Any change in the primary structure (i.e., the sequence of amino acids) creates a different protein.

Secondary Structure

• The secondary structure of a protein refers to the shape of a long polypeptide chain.
• There are two types of secondary structures: α-helix and β-pleated sheet structure.
• These structures arise due to the regular folding of the polypeptide chain backbone due to hydrogen bonding between –NH– and –C=O groups of the peptide bond.
• α-Helix is a common way in which a polypeptide chain forms all possible hydrogen bonds by twisting into a right-handed screw (helix) with the –NH group of each amino acid residue hydrogen bonded to the –C=O of an adjacent turn of the helix.
• β-Pleated sheet structure involves peptide chains stretched out to nearly maximum extension and laid side by side, held together by intermolecular hydrogen bonds, resembling the pleated folds of drapery.