Question

1. with your group, using grammatically correct sentences, define the following.

a. tertiary protein structure.
occurs when certain attractions are present between the alpha helices, pleated sheets
b. quaternary protein structure.
occurs when more than one amino - acid chain interact to form the overall rorchorool protein

1. imagine a protein chain that includes the following amino acids among several others.

serine
cysteine
asparagine
phenylalanine
a. which of the amino acids could form a hydrogen bond with another amino acid in the chain to stabilize the secondary structure of a β - pleated sheet?
b. which of the amino acids could form disulfide bonds with another amino acid in the chain to stabilize the tertiary structure of the protein?
c. which of the amino acids could participate in hydrophobic interactions with another amino acid in the chain to stabilize the tertiary structure of the protein?
d. what types of bonds or interactions could asparagine form with another amino acid in the chain in order to form a quaternary structure with another protein chain?

Explanation:

a. Hydrogen - bonding in β - pleated sheets occurs between polar side - chains. Serine has a polar - OH group and asparagine has a polar amide group, so they can form hydrogen bonds.
b. Disulfide bonds are formed between cysteine residues as they have a thiol (-SH) group that can oxidize to form a disulfide (-S - S -) bond.
c. Hydrophobic interactions involve non - polar side - chains. Phenylalanine has a non - polar aromatic side - chain and can participate in hydrophobic interactions.
d. Asparagine can form hydrogen bonds (due to its amide group) and van der Waals forces with other amino acids to contribute to quaternary structure formation.

Answer:

a. Serine, Asparagine
b. Cysteine
c. Phenylalanine
d. Hydrogen bonds, van der Waals forces