BB3 Tertiary Quaternary Structure

Question 0

Examples of proteins w/ single polypeptide chain

Answer 0

• myoglobin

* concanavalin A

Question 1

Tertiary Structure of a protein

Answer 1

the spatial arrangement of amino acids usually far apart from each other in the linear sequence

Question 2

Native Structure of a Protein

Answer 2

a 3-D structure of a protein when in a physiological environment

Question 3

RNase A

Answer 3

• 124 amino acids
• 4 disulfide bonds
• hydrolyzes RNA
• digestive enzyme

Question 4

Hydrolysis

Answer 4

cleavage of chemical bonds by addition of water

Question 5

Orthologs

Answer 5

• identical structures across different species

* similar secondary structure

Question 6

Paralogs

Answer 6

• similar structural appearance, but carries out different function
• same species

Question 7

Proteins lose their structure (denature) in

Answer 7

• Urea 8M

* Guanidine Hydrochloride 6M

Question 8

Unfolded protein

Answer 8

random coil

Question 9

Urea and guanidine hydrochloride disrupt…

Answer 9

noncovalent bonds

Question 10

Reducing agent which breaks disulfide bonds

Answer 10

beta-mercapto ethanol

donates electrons

Question 11

Conclusion of Anfinsen’s Experiment #1

Answer 11

• the amino acid sequence of RNase A provides the info needed to specify its native structure
• the primary structure of a protein dictates its tertiary structure

Question 12

Conclusion of Anfinsen’s Experiment #2

Answer 12

• the thermodynamically most stable structures of RNase A is its native structure
• true for all proteins

Question 13

Quaternary Structure of a protein

Answer 13

the spatial arrangement in a protein made up from more than one polypeptide chain

Question 14

Each chain of a protein is a …

Answer 14

subunit

Question 15

Hemoglobin’s quaternary structure

Answer 15

• 4 separate polypeptide chains – 2 alpha subunits, 2 beta subunits

Question 16

Reasons for quaternary structure

Answer 16

smaller quantities of genetic material to create larger proteins and structures

Question 17

Quaternary structure is excellent for

Answer 17

regulating protein function (allosteric effect)

Question 18

Allosteric effect

Answer 18

change in one subunit induces a change in another

Question 19

Protein conformation

Answer 19

The 3D arrangement of a proteins atoms in its structure
•independent of number of chains in the protein
•not always in native conformation

Question 20

Principal factor governing folding

Answer 20

• burying of hydrophobic side chains

* forms protein core

Question 21

Levinthal’s Paradox

Answer 21

• proteins don’t fold via a random pathway
• fold to native structures via formation of a stable partially correct secondary structure features as intermediate stages in folding

Question 22

Anfinsen - Experiment 1

Answer 22

• dissolve RNase A in betamercaptoethanol and 8M Urea (denature) = loses enzyme activity
• remove BOTH betamercaptoethanol and 8M Urea by dialysis
• oxidize cysteine = reform disulfide bond
== regains all activity

Question 23

Anfinsen - Experiment 2

Answer 23

• denature RNase A
• remove ONLY betamercaptoethanol
• retain 8M urea
• regains 1% activity bc only 1 correct arrangement of disulfides in 105
• add trace amounts of betamercaptoethanol = disulfide bonds rearrange = regains enzymatic activity
• thermodynamics drives protein to its native structure