Protein denaturation

Heat

Secondary: Disrupts H-bonding that keeps A-helix and B-sheets together

Tertiary: H-bonding disruption and hydrophobic interactions are disrupted by the increase of KE in atoms

Quaternary: Disrupted if held by non-covalent forces

Change in pH

Secondary: H-bond disruption can disrupt A-helix and B-sheet structures

Tertiary: destabilizes ionic bonds which stabilize the tertiary structure, H-bonds disruption alters it as well. This happens due to change in altering in amino acid side chains

Quaternary: If held by non-covalent structure

Urea/Guanidine

Secondary: disrupted due to H-bonding disruption

Tertiary: Unfolded because non-covalent interactions are disrupted. makes hydrophobic (non-polar) side chains more polar, causing them to move out of the protein's core. This disrupts the protein's shape and causes it to unfold.

Quaternary: Subunit broken apart if held by non-covalent forces

Detergents (SDS)

secondary: There is minor disruption, it may persist in presence

Tertiary: binds to the hydrophobic regions of a protein, preventing non-polar side chains from clustering together in the hydrophobic core. This disrupts hydrophobic interactions, causing the protein to unfold and become a linear, negatively charged molecule.

Quaternary: disrupted if held by non-covalent forces

Beta- Mercaptoethanol (BME)

Secondary: can be disrupted by tertiary and quaternary are the one that are affected the most

Tertiary and secondary: reduces disulfide bonds (covalent bonds between cysteine residues) that help stabilize the protein's structures. By breaking these covalent bonds it unfolds the protein, disrupting both its 3D shape and interactions between subunits in multimeric proteins.

Alcohol

Secondary: H-bonds are disrupted and A-helix and B-sheets are disrupted due to this

Tertiary and quaternary: disrupts hydrogen bonds and weakens hydrophobic interactions in proteins. This denatures proteins by causing them to unfold and lose their structure. can also alter the solubility of hydrophobic regions, leading to a loss of protein function.