Protein Structure and Denaturation

Flashcards about protein structure and denaturation

What role does proline serve in secondary structure?

Proline's rigid structure causes it to introduce kinks in alpha helices or create turns in beta pleated sheets.

Describe the key structural features of alpha helix and beta pleated sheets.

The alpha helix is a rod-like structure in which the peptide chain coils clockwise around a central axis. In beta pleated sheets, the peptide chains lie alongside one another forming rows or strands held together by intramolecular hydrogen bonds between carbonyl oxygen atoms on one chain and amide hydrogen atoms in an adjacent chain.

What are the definitions of tertiary and quaternary structure and how do they differ in subtypes and the bonds that stabilize them?

Tertiary structure is the three-dimensional shape of a single protein molecule, stabilized by hydrophobic interactions, acid-base/salt bridges, disulfide links, van der Waals forces, hydrogen bonds, ionic bonds, and covalent bonds. Quaternary structure involves interactions between separate subunits of a multi-subunit protein, stabilized by the same bonds as tertiary structure.

Why do hydrophobic residues in a polypeptide move to the interior of the protein?

Moving hydrophobic residues to the interior of a protein increases entropy by allowing water molecules on the surface of the protein to have more possible positions and configurations, which stabilizes the protein.

List three different prosthetic groups that can be attached to a protein and name the conjugated protein.

Examples of prosthetic groups include lipids, carbohydrates, and nucleic acids, leading to lipoproteins, glycoproteins, and nucleoproteins, respectively.

Why are proteins denatured by heat and solutes, respectively?

Heat denatures proteins by increasing their average kinetic energy, disrupting hydrophobic interactions. Solutes denature proteins by disrupting elements of secondary, tertiary, and quaternary structure.