Amino Acids

Question 1

Valine

Answer 1

(Val) Aliphatic, highly hydrophobic

Question 2

Leucine

Answer 2

(Leu) Aliphatic, highly hydrophobic

Question 3

Isoleucine

Answer 3

(Ile) Aliphatic, highly hydrophobic

Question 4

Phenylalanine

Answer 4

(Phe) Aromatic, absorbs weakly at 280 nm, highly hydrophobic

Question 5

Tryptophan

Answer 5

(Trp) Aromatic - heterocyclic, absorb strongly at 280 nm, hydrophobic, bulky, forms H bonds (donor)

Question 6

Methionine

Answer 6

(Met) hydrophobic, sulphur containing (thioether)

Question 7

Proline

Answer 7

(Pro) aliphatic, cyclical, secondary amino group, hydrophobic

Question 8

Serine

Answer 8

(See) polar, contains hydroxyl group, donor and acceptor

Question 9

Glycine

Answer 9

(Glycolic) achiral, weakly polar, very small - flexible

Question 10

Threonine

Answer 10

(The) polar, has hydroxyl group, donor and acceptor, can be phosphorylated

Question 11

Tyrosine

Answer 11

(Tyr) weakly polar, aromatic group, absorbs at 280 nm, is phenol, has hydrophobic interactions but not classified as hydrophobic, contains hydroxyl group, donor and acceptor, can be phosphorylated
pka = 10.5

Question 12

Cysteine

Answer 12

(Cys) polar, sulfur containing (sulfhydryl), donor, can for thiolate anion (S-), form disulphide bond with another CYS
pka = 8.5

Question 13

Asparagine

Answer 13

(Asn) has amide (carboxamide), polar, forms H bonds, donor with N, acceptor with O

Question 14

Glutamine

Answer 14

(Gln) has amide (carboxamide), polar, is donor and acceptor

Question 15

Histidine

Answer 15

(His) side chain can be basic or acidic at neutral pH, imidazole ring, aromatic, absorbs weakly at 280, polar, donor and acceptor, involved in enzymatic reactions
pka = 6.0

Question 16

Aspartate

Answer 16

(Asp) negative at pH 7, very polar, forms h bonds, at pH 1 = aspartic acid
pka = 4.0

Question 17

Glutamate

Answer 17

(Glu) negative at pH 7, very polar, forms h bonds (acceptor), at pH 1 = glutamic acid
pka = 4.0

Question 18

Lysine

Answer 18

(Lys) positive at pH 7 , basic amino group, is H bond donor, very polar
pka = 10.5

Question 19

Arginine

Answer 19

(Arg) positive at pH 7, quango group, never deprotonated under physiological conditions, very polar, H bond donor
pka = 12.5

Question 20

Alanine

Answer 20

(Ala) aliphatic, hydrophobic