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Flashcards in Proteins Deck (22):
1

What is the structure of an amino acid?

Amino group, side chain, carboxyl group.

2

How many amino acids exist?

20

3

What is a hydrophobic amino acid?

Has a non-polar side chain.

4

Give examples of hydrophobic amino acids

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.

5

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

Hyrdophillic

6

Give examples of hydrophillic amino acids

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

7

What amino acids have charged side chains?

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)

8

What is buffering capacity and why is it used?

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.

9

What chirality are the amino acids found in?

All amino acids found in proteins exist in the L Form

10

What is the only non chiral amino acid?

Glycine

11

What reaction forms peptides?

Condensation reaction

12

What is the anatomy of a peptide?

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

13

What are the characterstics of a peptide bond?

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

14

What bonds hold a protein together?

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)



15

What holds alpha helicies and beta pleated sheets together?

Hydrogen bonds

16

What amino acid is kinky and why?

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

17

What denaturants break down proetin into the polypeptide?

Urea for H-Bonds
2-Mercaptoethanol (S-S Bonds)

18

How does warfarin work?

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.

19

What is secondary structure?

Local structural motifs within a protein

20

What is tertiary structure?

Arrangement of secondary motifs into compact globular structures called domains

21

What is quaternary structure?

3D structure of a multimeric protein composed of several subunits

22

What is post translational modification used for?

To create novel amino acids enhancing the capabilities of the protein