Peptides

Question 1

AMPHOTERIC

Answer 1

Act as acids or bases

Question 2

ISOELECTRIC POINT

Answer 2

NET CHARGE = 0
ZWITTERION

pH 6.5-7.5

Question 3

NON-POLAR NEUTRAL AMINO ACIDS

Answer 3

No charge/EN atoms
Cannot H bond
WATER INSOLUBLE

ALIPHATIC: Ala, Ile, Leu, Met, Val
AROMATIC, Phe, Trp, Tyr
UNIQUE: Gly, Pro

Question 4

POLAR NEUTRAL AMINO ACIDS

Answer 4

Partial charges - can H bond
Water SOLUBLE

Asn, Cys, Gln, Ser, Thr

Question 5

CHARGED AMINO ACIDS

Answer 5

Charged side chains can H & ionic bond
V WATER SOLUBLE

ACIDIC: Asp, Glu
BASIC: Arg, His, Lys

Question 6

Calculate pI

Answer 6

pI = (pKa1​+pKa2​)/2

Question 7

Acidic pI is ___ than pKa

Answer 7

lower

Question 8

Basic pI is ___ than pKa

Answer 8

higher

Question 9

State 3 methods of aa separation

Answer 9

ELECTROPHORESIS (pI)
CHROMATOGRAPHY (polarity)
ION EXCHANGE CHROMATOGRAPHY

Question 10

State 2 methods of aa synthesis

Answer 10

From α-halo acids

Strecker synthesis

Question 11

Why are peptide bonds so stable?

Answer 11

RESONANCE STABILISED

Question 12

Peptide synthesis

Answer 12

SOLID PHASE SYNTHESIS

Question 13

outline phases of SOLID PHASE SYNTHESIS

Answer 13

N-DEPROTECTION, C-ACTIVATION, COUPLING, CLEAVAGE.

Question 14

PRIMARY STRUCTURE

Answer 14

AMINO ACID SEQUENCE in chain & location of disulfide bonds

Question 15

SECONDARY STRUCTURE

Answer 15

CONFORMATIONS due to folding interactions

ALPHA HELIX or BETA PLEATED SHEETS

Question 16

TERTIARY STRUCTURE

Answer 16

3D FOLDING due to disulfide & H bonds, ELECTROSTATIC & HYDROPHOBIC interactions.

Question 17

QUATERNARY

Answer 17

ARRANGEMENT of subunits with respect to each other.

Question 18

2 categories of proteins

Answer 18

FIBROUS & GLOBULAR

Question 19

D isomers

Answer 19

(+) R-enantiomer

α-C , -OH RIGHT

Question 20

L isomer

Answer 20

(-) S-enantiomer

α-C , -OH LEFT