biochem amino acids

glycine

G, Gly

alanine

A, Ala

valine

V, Val

leucine

L, Leu

isoleucine

I, Ile

methionine

M, Met

proline

P, Pro

phenylalanine

F, Phe

tyrosine

Y, Tyr

tryptophan

W, Trp

serine

S, Ser

threonine

T, The

cysteine

C, Cys

asparagine

N, Asn

glutamine

Q, Gln

aspartate

D, Asp

glutamate

E, Glu

lysine

K, Lys

arginine

R, Arg

histidine

H, His

Nonpolar, Aliphatic side chains

glycine, alanine, valine, leucine, isoleucine, methionine, proline

Aromatic Side Chains

Phenylalanine, tyrosine, tryptophan

Polar, uncharged side chains

serine, threonine, cysteine, asparagine, glutamine

negatively charge side chain

aspartate, glutamate

positively charge side chains

lysine, arginine, histidine

Structure and Charge of an a-carbonyl group when protonated vs deprotonated?

Protonated: -COOH (0 Charge)

Deprotonated: -COO- (-1 Charge)

Structure and charge of an a-amino group when protonated vs deprotonated?

Protonated: -NH3+ (Charge +1)

Deprotonated: -NH2 (Charge 0)

Structure and Charge of Asp/Glu side chains when protonated vs deprotonated?

Protonated: -CH2-COOH (charge 0)

Deprotonated: -CH2-COO- (Charge -1)

structure and charge of His side chain when protonated vs deprotonated?

Protonated: ring with protonated, positive nitrogen (charge +1)

Deprotonated: neutral ring (charge 0)

~pKa of all a-carbonyl group

2

~pKa of acidic side chains (asp, glu)

4

~ pKa of his side chain

6

~pKa of Cysteine’s thiol side chain

8

~pKa of all a-amino groups

9.5

~pKa of basic side chains (lys, arg)

10.5/12.5

which amino acids have branched alkyl side chain

valine, leucine, isoleucine

which amino acid chain absorb uv light strongly at 280 nm

tryptophan and tyrosine

which amino acids is completely chiral

Glycine, its R group is just a hydrogen atom

which amino acid contains a thioether sulfur atom but is not capable of forming disulfide bonds

methionine. only cysteine has a free thiol to form covalent disulfide crosses