Exam 1

Question 1

Amino acids with absorbance at 280 nm

Answer 1

tyr, trp

Question 2

Amino acid with absorbance at 260 nm

Answer 2

phe

Question 3

___________ cleaves disulfide bond

Answer 3

2-mercaptoeethanol / BME

Question 4

__________ prevents re oxidation

Answer 4

iodoacetate

Question 5

which amino acid can form disulfide bonds

Answer 5

cys

Question 6

Non polar amino acids (9)

Answer 6

gly, ala, trp, met, pro, ile, leu, val, phe

Question 7

Polar (-) amino acids (2)

Answer 7

asp, glu

Question 8

Polar (+) amino acids (3)

Answer 8

lys, his, arg

Question 9

Polar uncharged amino acids (6)

Answer 9

tyr, gln, asn, cys, thr, ser

Question 10

Gas phase ions of peptides and proteins are _______ at basic residues to give a positive charge

Answer 10

protonated

Question 11

Right handed helix turn length

Answer 11

5.4 angstroms

Question 12

C-C bond length

Answer 12

1.5 angstroms

Question 13

C-H bond length

Answer 13

1 angstrom

Question 14

How many atoms are in the amide plane

Answer 14

6

Question 15

Why aren’t the bonds in the amide plane trigonal planar

Answer 15

because the bond angles are not 120

Question 16

______ makes hemoglobin lose affinity for oxygen

Answer 16

BPG

Question 17

Cooperativity

Answer 17

the concept that one hb subunit binding an O2 will cause the other subunits to want to bind an O2 so binding affinity for hb increases

Question 18

Bohr

Answer 18

high pH = high affinity for R state
low pH = high affinity for T state

Question 19

Sickle cell is caused by what amino acid substitution

Answer 19

glu -> val

Question 20

Disulfide isomerase

Answer 20

breaks sulfide bonds to correct errors in amino acid sequence and then helps reform the broken bond

Question 21

Lysyl oxidase

Answer 21

modifies and cross links collagen side chains

Question 22

Collagen disorders

Answer 22

Ehlers-Danlos
Scurvy
Osteogenesis imperfecta

Question 23

Purification used for separating by charge-

Answer 23

ion exchange chromatography

Question 24

Purification used for separating based on solubility

Answer 24

salting out

Question 25

Purification used for separating by size

Answer 25

gel filtration chromatography / SDS PAGE

Question 26

Purification used for separating by binding specificity

Answer 26

affinity chromatography

Question 27

Which chromatography has a gradient

Answer 27

ion exchange

Question 28

PITC

Answer 28

modifies N terminus via TFA

Question 29

Trypsin

Answer 29

cleaves at K and R unless the following amino acid is P

Question 30

Imidazolium ions

Answer 30

neutral when protonated, negative when deprotonated

Question 31

Amino acids most likely to be found in a-helix

Answer 31

ala, glu, met

Question 32

Amino acids most likely to be found in b-pleated sheet

Answer 32

ile, tyr, val

Question 33

Cyanogen bromide cleaves _____ residue

Answer 33

met

Question 34

How many amino acid residues per turn of an a-helix

Answer 34

3.6

Question 35

_________ stabilize collagen helix

Answer 35

covalent cross-links

Question 36

pH for a buffer must be

Answer 36

comfortably below the pI

Question 37

Protein with the ______ pI will come out first when using ion exchange chromatography

Answer 37

lowest

Question 38

If pH > pI the protein will be _____ charged and you should use _______ exchange chromatography

Answer 38

negatively, cation

Question 39

If pH < pI the protein will be _____ charged and you should use ______ exchange chromatography

Answer 39

positively , anion

Question 40

Techniques to find protein structure

Answer 40

crystallography, NMR

Question 41

Scurvy

Answer 41

low levels of vitamin C lead to lower hyp production

Question 42

Collagen mutations (osteogenesis imperfecta)

Answer 42

any substitution of gly can disrupt collagen formation

Question 43

Ehlers-Danlos syndrome

Answer 43

Mutation of collagen maturation enzymes failure to cross-link collagen causes destabilized collagen fibers and hyper-elasticity