Protein Structure

Question 1

Size of Proteins

Answer 1

much smaller than nucleic acids

comparable in size to tRNA (smallest of nucleic acids)

Question 2

Average size of proteins

Answer 2

15,000 to 70,000 MW range

135 to 635 AA in the sequence

Question 3

Protein structure Structure

Answer 3

• not as uniform as DNA

- unique for each protein species

Question 4

Peptide bond

Answer 4

between amino and carboxyl groups on adjacent amino acids

Question 5

Rules for folding

Answer 5

still in development, computer modeling

Question 6

Primary structure

Answer 6

amino acid sequence

Question 7

Secondary structure -

Answer 7

α helix
β structure
Hydrogen bonding between peptide groups

Question 8

fibrous proteins

Answer 8

secondary structure

lots of α and β structure

Question 9

globular proteins

Answer 9

secondary structure

limited to short runs of α and β structure

Question 10

Tertiary structure or tertiary folding

Answer 10

side chain interactions
results in extensive folding of the backbone
ex. ionic bonds, hydrophobic clustering, disulfide bonds – very stable

Question 11

Quaternary structure

Answer 11

subunits clustered together-usually identical subunits but not always
2-6 subunits most common

Question 12

reasons for quaternary structure

Answer 12

1. Economical use of DNA
   ex. 6000 AA - 18000 base pairs
   6 identical subunits - 3000 base pairs
2. Regulatory control - activity is very efficient and can be rapidly switched on and off
   ex. RNA polymerase, other enzymes involved with nucleic acids

Question 13

Enzymes- Binding Site

Answer 13

localized portion of protein responsible for interactions with other molecules
6-10 Å in size (Lock and key model vs induced fit model

Question 14

Enzymes- active site

Answer 14

binding site in enzymes - catalytically active region