Lecture 3: Amino Acid Structures

Question 1

Amino Acids and Protein Structure

Answer 1

• 20 amino acids that have distinct side chains that contribute to protein structure and function
• Non-covalent and covalent interactions between functional groups are important for holding protein together + interactions
• Interaction of hydrophilic amino acids with water help solubilize some proteins

Question 2

Amino acids

Answer 2

• Amino acids made up of an amino group, carboxyl group, and R side chain

Question 3

Chiral amino acids

Answer 3

• Asymetric alpha carbon results in chirality
• Chiral molecules are non-superimposable mirror images
• L amino acids are found in plant and animal proteins

Question 4

Non-covalent interactions

Answer 4

• Hydrogen bonds can form between hydroxyl, carboxyl, thiol, and amino groups
• Hydrogen bonds can form between amino acid side chains with protein structure
• Can occur between aliphatic and hydrophobic side chains

Question 5

Disulfide bonds

Answer 5

• Disulfide bonds covalently cross-link two cysteines together
• Disulfide bridges can be interchain or between different polypeptide chains
• Linkages stabilize structures
• Protein Disulfide Isomerase enzymes help catalyze oxidation reaction
• Disulfide bonds can be broken by reducing agents in cytosol or in lab(B-mercaptoethanol)

Question 6

Hydrophobic Amino Acids

Answer 6

• Hydrophobic amino acids can be found in the interior of proteins, maximizing number of hydrophilic interactions with water
• Hydrophobic amino acids can still be found on surface to allow for non-covalent interactions

Question 7

Post Translational Modification

Answer 7

• Additional or removal of functional groups can change structure of a protein and affect its function
• Disulfide bond formation is example of PTM