18. Amino Acids and Proteins

What level of protein structure is determined by the following:

a. Peptide bonds between amino acids?

What level of protein structure is determined by the following:

b. Hydrogen bonds between backbone carbonyl oxygen atoms and hydrogen atoms attached to backbone nitrogen atoms?

How do the following noncovalent interactions help to stabilize the tertiary and quaternary structure of a protein? Give an example of a pair of amino acids that could give rise to each interaction.

a. Hydrophobic interactions

Determine which of the following statements describes a tertiary structure of a protein.

Indicate whether each of the following statements describes a primary, secondary, tertiary, or quaternary protein structure:

______ a) Hydrophobic R groups seeking a nonpolar environment move toward the inside of the folded protein.  

______ b) Protein chains of collagen form a polypeptide chain composed of 3 alpha helices. 

______ c) An active protein contains 4 tertiary subunits. 

______ d) Two polypeptide chains held together by disulfide bridges. 

How do the following interactions help to stabilize the tertiary and quaternary structure of a protein? Give an example of a pair of amino acids that could give rise to each interaction.

b. Disulfide bonds