Primary → secondary → tertiary → quaternary structure
Click an amino acid to highlight · Adjust pH to test stability
Primary: Linear sequence of amino acids linked by peptide bonds. Secondary: Local folding into α-helices and β-sheets via hydrogen bonds. Tertiary: 3D folding driven by R-group interactions (hydrophobic, ionic, disulfide). Quaternary: Multiple polypeptide subunits assembled together. High temperature causes denaturation — unfolding of the structure.