Chapter 4: 3D structure of proteins.

Question 1

What are some themes of protein Structure? (TQ)

Answer 1

(Structure, signaling and Storage)

• 3D structure of a protein is determined by its amino acids sequence
• The function of a protein is dependent on its structure.
• The most important stabilizing force for protein structure are non-covalent interactions.
• Protein structures are not static, they are dynamic.

Question 2

What is a protein conformation?

Answer 2

• Spatial Arrangement of atoms in a protein

* Rotation around a bond changes the conformation.

Question 3

What is a native protein?

Answer 3

• Protein in their functional, folded conformation
• Most stable
• Has the lowest Gibbs Free energy (G)?

Question 4

What is responsible for a protein stability

Answer 4

• Proteins ability to maintain native conformation
• Held together by disulfide bonds (covalent bonds between cysteine) and
• weak (noncovalent) interactions (H bonds, electrostatic interactions, hydrophobic interaction.

Question 5

What are polypeptides?

Answer 5

• Series of AA (called residues) joined by peptide bonds
• Specified by genes.
• Polypeptide backbones rich in carbonyls (C=O) and amino (N-H) which are great at hydrogen bonding
• Determines secondary and tertiary and quaternary structure as well as its function.

Question 6

Primary Structure

Answer 6

AA Sequence

Primary level of structure.