Tertiary Protein Structure Practice Problems

True or False: α-keratin and tropocollagen have the same secondary and tertiary structure and only mainly differ in their amino acid composition.

Amino acid side chain interactions primarily influence the overall shape of proteins. Among the following pairs of amino acids, identify which participate in hydrophobic interactions.

i. Ser · · ·Thr

ii. Leu · · · Ala

iii. Val · · · Ile

iv. Lys · · · Glu

Identify the type of molecular interactions or bonds formed between the side chains of the amino acids methionine and valine.

Determine the type of bond formed between the side chains of lysine and aspartic acid.

For each of the following pairs of amino acids, indicate whether the bond formed between their side chains is covalent or noncovalent.

i. Lysine and glutamine

ii. Asparagine and threonine

iii. Cysteine and cysteine

iv. Valine and phenylalanine

Which of the following is primarily responsible for the influence of glutamine on the tertiary structures of proteins? 

Octreotide is a growth hormone inhibitor, and it is used to treat disorders caused by excess growth hormone. It is a polypeptide with a primary structure of Phe-Cys-Phe-Trp-Lys-Thr-Cys-Thr. Its structure has a cyclic configuration held by a disulfide bridge. Using their abbreviations, the structure of octreotide and show the disulfide bridge.

Identify the noncovalent interaction that results in proteins folding into a globe-like shape, forming a 'water-loving' exterior. Give two examples of amino acids that will have this interaction.