Amino Acid Structures/Pka

Question 1

Glycine

Answer 1

R = Hydrogen
Disrupts secondary protein structure by creating kinks in alpha-helix b/c so flexible
Symbol: Gly, G

Question 2

Alanine

Answer 2

R = Methyl (CH3)
canonical example of simple, small, nonpolar AA
Symbol: Ala, A

Question 3

Valine

Answer 3

R = (C3 in a V)
substitution for glutamic acid causes sickle cell anemia
Symbols: Val, V

Question 4

Isoleucine

Answer 4

R = C3 w/ a methyl on the 1’
our bodies can’t synthesize, we have to eat
Symbols: Ile, I

Question 5

Leucine

Answer 5

R = C3, w/ a methyl on the 2’ - just valine with one more carbon before the V
our bodies can’t synthesize, we have to eat
Symbols: Leu, L

Question 6

Methionine

Answer 6

R = C2, S, methyl
has a thioether bond (S-C)
not really considered nonpolar
involved in angiogenesis and DNA methylation
symbols: Met, M

Question 7

Proline

Answer 7

R = secondary alpha-amino group - the alkyl group forms a bond with the amino group of the protein backbone - 3 C then, connect with N
Disrupts secondary protein structure by creating kinks in alpha-helix
Symbols: Pro, P

Question 8

Phenylalanine

Answer 8

R = methyl group + benzene ring
if you have phenylketonuria, you can’t convert this to tyrosine
symbols: Phe, F

Question 9

Cysteine

Answer 9

R = C and a Thiol group
Can form disulfide bridges in oxidizing environments (extracellular env) (deprononated and then the neg charged Sulfurs form a covalent bond)
Reduced form = Cysteine
Oxidized from - Cystine
Symbols: Cys, C

Question 10

Histidine

Answer 10

R = C2 + imidazole side chain
good protein stabilizer b/c it can exists in both protonated and deprotonated forms at physiological pH (the N can be N or NH+)
Symbols: His, H

Question 11

How do pH and pKa determine protonation?

Answer 11

pH>pKa = deprotonated form

pH

Question 12

Tyrosine

Answer 12

R = methyl + benzene + hydroxyl at 4’ (a phenol)
more water soluble than F, but still nonpolar
precursor for dopamine, epinephrine and norepinephrine
Symbols = Tyr, Y

Question 13

Tryptophan

Answer 13

R = methyl + indole (cyclic 4 carbon + amine group with 2 carbons shared with a benzene ring)
Symbols = Trp, W

Question 14

Serine

Answer 14

R = single-carbon alcohol (ch2oh)
polar
often target for phosphorylation and post-translation modification + signaling
we can make it from glycine
Symbols = Ser, S

Question 15

Threonine

Answer 15

R = two carbon alcohol (C2, with a secondary hydroxyl group)
can’t make from glycine
Symbols = Thr, T

Question 16

Asparagine

Answer 16

R = C + amide (one of 2 AAs that is an amide)
Symbols = Asn, N

Question 17

Glutamine

Answer 17

R = C2 + amide
most common free AA in human blood
Symbols = Gln, Q

Question 18

Arginine

Answer 18

R = C3 + guanidium group (NHC(NH2+)NH2)
guanidium group positively charged
stabilized by resonance, so it’s the most basic of all AAs
Symbols = Arg, R

Question 19

Lysine

Answer 19

R = C4 and a primary amine
positively charged and reactive - target of methylation and acetylation
Symbol = Lys, K

Question 20

Aspartic Acid (Aspartate)

Answer 20

R = C and a carboxyl group
exists in the oxidized form (deprotonated) at biological pH (so neg charged)
Symbols = Asp, D

Question 21

Glutamic acid

glutamate

Answer 21

R = C2 + carboxyl group
Symbols = Glu, E

Question 22

What amino acids are keteogenic?

Answer 22

ketogenic = can be directly converted into Acetyl-CoA or Acetoacetyl-CoA
they are Leucine (L) and Lysine (K)

Question 23

What amino acids are glucogenic?

Answer 23

Glucogenic = are metabolized to yield pyruvate or krebs cycle intermediates
Alanine (A)
Arginine (R)
Asparagine (N)
Aspartate (D)
Cysteine (C)
Glutamic Acid (E)
Glycine (G)
Histidine (H)
Valine (V)
Methionine (M)
Proline (P)
Serine (S)