Lecture 16

Question 1

what are the different types of globular proteins?

Answer 1

1. catalysis- enzymes
2. regulatory- hormones
3. defense-antibodies
4. transport in blood- albumin
5. oxygen delivery- hemoglobin

Question 2

What are the different kinds of structural proteins?

Answer 2

1. extracellular matrix- collagen and elastin
2. contractile- actin and myosin
3. signal transduction-specific receptors

Question 3

types of covalent bonds?

Answer 3

peptide and disulfide

Question 4

types of non-covalent bonds?

Answer 4

hydrophobic interactions
hydrogen bonds
ionic bonds

Question 5

What amino acids will participate in hydrophobic interactions?

Answer 5

valine, leucine, isoleucine, alanine

and phenylalanine

Question 6

What do hydrogen bonds do during protein folding?

Answer 6

stabilize the secondary structures of a-helix and b-sheet
Hydrogen bonds between amino acid side chains
stabilize the tertiary structure of proteins

Question 7

What is the purpose of chaperones or heat shock protiens?

Answer 7

1. help fold proteins that do not fold by themselves
2. bind to aggregated proteins
3. unfold and refold misfolded proteins
4. Direct proteins to degradation in proteasomes and lysosomes

Question 8

What is the function of Hsp 70?

Answer 8

prevents the aggregation of unfolded protein.

It binds to hydrophobic regions of an extended
polypeptide and prevents premature folding of
a protein

Question 9

What is the function of Hsp 60?

Answer 9

have a barrel shape and are required for correct folding of cellular proteins that do not fold spontaneously

Hsp 60 can be used to aid refolding of a protein after it has crossed a cellular membrane.

This needs ATP

Question 10

Ubiquitin-Proteasome Complex

Answer 10

Misfolded or defective proteins are normally tagged
by the small protein ubiquitin and degraded in the
ubiquitin-proteasome system

ATP dependent

Question 11

When does piron disease occur?

Answer 11

When the normal prp protein changes 3-D conformation due to changes in secondary structure

normal prp = more alpha helices

mutated prp = more beta sheets

Question 12

Routes of transmission of piron disease?

Answer 12

1. genetic
2. ingestion of infected meat
3. blood transfusion
4. brain surgeries and procedures
5. injection of infected human growth hormone

Question 13

How can hydrogen bonds be broken?

Answer 13

high temperature, 5-10 M urea, or salt

Question 14

how are hydrogen and ionic bonds broken?

Answer 14

strong acids or bases.

Question 15

How are hydrophobic interactions broken?

Answer 15

1-2% of the detergent Sodium dodecyl sulfate (SDS)

Question 16

How are disulfide bonds broken?

Answer 16

β-mercaptoethanol