Proteins

Question 1

What is the structure of an amino acid?

Answer 1

Amino group, side chain, carboxyl group.

Question 2

How many amino acids exist?

Answer 2

20

Question 3

What is a hydrophobic amino acid?

Answer 3

Has a non-polar side chain.

Question 4

Give examples of hydrophobic amino acids

Answer 4

Glycine (H), Alanine (CH3), Proline, Valine(CH(CH3)2): Giant Anal Proplapses Vary.
Leucine, Isoleucine, Methionine (CH2CH2SCH3), Tryptophan, phenylalanine. Leucine anad Isoleucine may take pharmacology.

Question 5

What is an amino acid with a polar side chain called?

Answer 5

Hyrdophillic

Question 6

Give examples of hydrophillic amino acids

Answer 6

Serine (CH2OH), Threonine (CCH3HOH), Tyrosine, Aspargine, Glutamine, Cysteine (CH2SH)

Question 7

What amino acids have charged side chains?

Answer 7

Lysine ((CH2)4NH3+), Anrginine, Histidine.
Lysine and Arginine are ALWAYS PROTONATED (basic) at physiological pH
Histidine is protonated below pH 6.0.

Glutamate and Aspartate are ALWAYS NEGATIVELY CHAGRED (proton donation) at physiological pH (CO2)

Question 8

What is buffering capacity and why is it used?

Answer 8

It is the the ability of amino acids to take up and release protons and allows them to resist some pH changes so that there is not a loss of biological activity.

Question 9

What chirality are the amino acids found in?

Answer 9

All amino acids found in proteins exist in the L Form

Question 10

What is the only non chiral amino acid?

Answer 10

Glycine

Question 11

What reaction forms peptides?

Answer 11

Condensation reaction

Question 12

What is the anatomy of a peptide?

Answer 12

Amino terminus (NH2)
Peptide bond (C=ONH) 
Carboxyl terminus (C=OOH)

Question 13

What are the characterstics of a peptide bond?

Answer 13

No free rotation
C=O and N-H bonds in same plane
Other bonds in backbone of peptide CAN rotate
Only conformations with no steric hindrance is allowed

Question 14

What bonds hold a protein together?

Answer 14

Covalent bonds (can exist as disulphide bridges)

Hydrogen bonds (“ atoms with partial - charge share a partially + H atom)

Ionic interactions (electrostatic attraction between CHARGED SIDE CHAINS)

Van der Waals Forces (transient weak electrostatic attractions)

Hydrophobic interactions (Where hydrophoibc chains pack in interior or protein, hydrophillic on outside)

Question 15

What holds alpha helicies and beta pleated sheets together?

Answer 15

Hydrogen bonds

Question 16

What amino acid is kinky and why?

Answer 16

Proline, NH grp is lost, side chain cannot H-Bond with C=O grps, distorting helical conformation (puts KINK in it)

Question 17

What denaturants break down proetin into the polypeptide?

Answer 17

Urea for H-Bonds

2-Mercaptoethanol (S-S Bonds)

Question 18

How does warfarin work?

Answer 18

Carboylation of glutamic acid in proteins of blood clotting cascade e.g. factor IX) important for normal function by increasing calcium bonding capabilities.
Inhibits carboxylation reaction, is an anticoagulant so coagulation factors cannot bind to phospholipid surfaces inside blood vessels on vascular endothelium.

Question 19

What is secondary structure?

Answer 19

Local structural motifs within a protein

Question 20

What is tertiary structure?

Answer 20

Arrangement of secondary motifs into compact globular structures called domains

Question 21

What is quaternary structure?

Answer 21

3D structure of a multimeric protein composed of several subunits

Question 22

What is post translational modification used for?

Answer 22

To create novel amino acids enhancing the capabilities of the protein