Amino Acids

Aliphatic (GAVL)

Glycine, Alanine, Valine, Leucine

Aliphatic Ring

Proline

4 Stereoisomers

Isoleucine

Characteristic of Aliphatics

Hydrocarbon chains and are generally non polar

Aromatics (WYF)

Tryptophan, Tyrosine, Phenylalanine

Characteristic of Aromatics

Contain a benzene ring and are visible in the light spectrum

Sulfur-Containing (MC)

Methionine, Cysteine

Characteristic of Sulfur-Containing

Cysteine can form disulfide bridges with other cysteines

Alcohol Groups (ST)

Serine, Threonine

Characteristic of Alcohol Groups

Have uncharged, highly polar side chains

Basic (HKR)

Histidine, Lysine, Arginine

Characteristic of Basic

Side chains contain nitrogenous bases which are substantially positively charged at pH-7

Base strength in order: H < K < R

Acidic (ED)

Glutamate, Aspartate

Characteristic of Acidic

Have an extra carboxylic acid group that is negatively charged at pH-7

Amides (QN)

Glutamine, Asparagine

Characteristic of Amides

Have a ketone and an amide group

Glycine (Gly, G)

Alanine (Ala, A)

Valine (Val, V)

Leucine (Leu, L)

Proline (Pro, P)

Isoleucine (Ile, I)

Tryptophan (Trp, W)

Tyrosine (Tyr, Y)

Phenylalanine (Phe, F)

Methionine (Met, M)

Cysteine (Cys, C)

Serine (Ser, S)

Threonine (Thr, T)

Histidine (His, H)

Lysine (Lys, K)

Arginine (Arg, R)

Glutamate (Glu, E)

Aspartate (Asp, D)

Glutamine (Gln, Q)

Asparagine (Asn, N)

Glycine (letter codes)

Gly, G

Alanine (letter codes)

Ala, A

Valine (letter codes)

Val, V

Leucine (letter codes)

Leu, L

Isoleucine (letter codes)

Ile, I

Proline (letter codes)

Pro, P

Tryptophan (letter codes)

Trp, W

Tyrosine (letter codes)

Tyr, Y

Phenylalanine (letter codes)

Phe, F

Methionine (letter codes)

Met, M

Cysteine (letter codes)

Cys, C

Serine (letter codes)

Ser, S

Threonine (letter codes)

Thr, T

Histidine (letter codes)

His, H

Lysine (letter codes)

Lys, K

Arginine (letter codes)

Arg, R

Glutamate (letter codes)

Glu, E

Aspartate (letter codes)

Asp, D

Glutamine (letter codes)

Gln, Q

Asparagine (letter codes)

Asn, N

Alpha Carboxyl pKa

1.8-2.5

Alpha Amine pKa

8.7-10.7

Histidine pKa

6

Lysine pKa

10.5

Arginine pKa

12.5

Glutamate pKa

4.1

Aspartate pKa

3.9

Cysteine pKa

8.4

Tyrosine pKa

10.5

Glycine Characteristic

Simplest AA with only an H as the R-group. Is also the only achiral

Alanine Characteristic

Just a methyl group as the R-group

Valine Characteristic

Isopropyl R-group (shaped like a V)

Leucine Characteristic

Has an isopropyl group but sticks out one carbon further than val

Proline Characteristic

Cyclopentane ring with a NH2+ group

Isoleucine Characteristic

Two chiral carbons

Tryptophan Characteristic

Two benzene rings

Tyrosine Characteristic

Benzene ring with an alcohol coming off (phenol group)

Phenylalanine Characteristic

Benzene ring as the R-group

Methionine Characteristic

Contains a sulfur but not add the end of the chain making it unable to form disulfide bridges

Cysteine Characteristic

Contains sulfur on the end of the R-group allowing for disulfide bridges to form

Serine Characteristic

There is only one carbon in the R-group and the alcohol is attached to it

Threonine Characteristic

Attached to the chiral beta carbon that has an alcohol, methyl, and H attached

Histidine Characteristic

Has a five membered ring where the NH with a lone pair can be donated in conjugate acid form

Lysine Characteristic

Has a 4 carbon chain with a positively charged NH3+ at neutral pH

Arginine Characteristic

Has a 3 carbon chain then a fourth carbon that is surrounded by nitrogens

Glutamate Characteristic

2 carbon chain with COO- at neutral pH

Aspartate Characteristic

1 carbon then COO- at neutral pH

Glutamine Characteristic

Glutamate with an amine where the OH/O- would’ve been

Asparagine Characteristic

Aspartate with an amine where the OH/O- would’ve been

Trypsin Cleavage

C-terminals of Lys and Arg

Chymotrypsin Cleavage

C-terminals of all the aromatic AAs; Tryptophan, Tyrosine, and Phenylalanine

(Chymo)Trypsin Cleavage exceptions

If there is a proline as an adjacent AA or if the AA is methyl/acteylated they will not be cleaved