Protein Structure Flashcards
What are the two common types of covalent bonds between amino acids in proteins?
peptide bonds and disulfide bridges
What is a peptide bond between in amino acids?
link amino acids together into polypeptide chains, located between the carboxyl group of one amino acid and the alpha-amino group of the other amino acid with the loss of water
What is the disulfide bridge between in amino acids?
between the cysteine R-groups, the thiol of one cysteine will react with the thiol of another cysteine
What is the term for an individual amino acid in the backbone of a polypeptide chain?
residue
What is proteolysis/proteolytic cleavage?
hydrolysis of a protein by another protein
What is the protein that performs proteolysis called?
proteolytic enzyme or a protease
What is a cysteine residue called once it becomes bonded to another cysteine residue?
cystine
What does denatured mean?
improperly folded proteins that are non-functional. it is the disruption of a protein’s shape without breaking peptide bonds.
How can proteins be denatured?
urea, extreme temperature, extreme pH, and by changes in salt concentration (tonicity)
What is the primary (1degree) structure of protein folding?
simplest level of protein folding where amino acids bond to each other in the polypeptide chain
What is primary structure of protein folding also known as?
sequence
What is the bond that determines the primary structure of protein folding?
peptide bond
What is the bond that forms the secondary structure of protein folding?
hydrogen bonds between backbone NH and CO groups
What are the common motifs formed from secondary structure in protein folding?
alpha-helix and beta-pleated sheet
What are the two problems in polypeptide chains caused by proline?
- formation of a peptide bond with proline eliminates the only hydrogen atom on the nitrogen atom of prole disrupting the backbone hydrogen bonding in the polypeptide chain
- the unique structure of proline forces it to kink the polypeptide chain
Which secondary motif does proline never form?
alpha-helix
Why is the alpha-helix a favorable structure for a hydrophic transmembrane region?
because all polar NH and CO groups in the backbone are hydrogen bonded to each other and on the inside of the helix
What are the two types of B-pleated sheets?
parallel
unparallel
What bonds are made during tertiary structure of protein folding?
van der waals forces
hydrogen bonds
disulfide bonds
electrostatic interactions
What drives the folding of secondary motifs into tertiary structures?
interactions between R-groups with each other and with solvent
What is the hydrophobic effect?
hydrophobic R-groups tend to fold into the interior of the protein away from the solvent while the hydrophilic groups tend to be exposed to water on the surface of the protein
What are the interactions in the quaternary structure of protein folding?
interactions between polypeptide subunits:
van der waals
hydrogen bonds
disulfide bonds
electrostatic interactions
