Question 1

Which is NOT important to size-exclusion chromatography?

Accepted Answer

A)  size of pores fond in resin beads 
B)  mesh size 
C)  hydrodynamic properties of proteins being separated 
D)  ionic properties of proteins being separated 
E)  column geometry

Question 2

A researcher adds a "tag" of several histidine residues to an engineered protein in order to purify the protein using

Accepted Answer

A)  size-exclusion chromatography 
B)  MAC 
C)  an immunoaffinity column 
D)  a cation exchange column 
E)  HIC

Question 3

Large quantities of proteins may be isolated from

Accepted Answer

A)  E.coli 
B)  yeast 
C)  plant tissue 
D)  animal tissue 
E)  All of the above

Question 4

A typical protein purification plan might maximally enrich a sample ___ fold above that found in the original cell lysate.

Accepted Answer

The answer of A typical protein purification plan might maximally...

Question 5

If a protein binds a specific ligand

Accepted Answer

A)  that ligand may be used to purify the protein in vitro 
B)  the ligand may interfere with studying the protein in situ 
C)  the ligand may interfere with protein folding 
D)  Both A and B 
E)  All of the above

Question 6

To yield sufficient biologics, pharmaceutical companies use ___ to grow sufficient cells, commonly with ____ versions of natural proteins.

Accepted Answer

The answer of To yield sufficient biologics, pharmaceutical companies use...

Question 7

In size exclusion chromatography, resins with small pore sizes will be able to resolve large molecules but not small ones. Therefore, the size of the pore must be matched to the estimated size of the protein to be purified.

Accepted Answer

A)  Both sentences are true 
B)  Both sentences are false 
C)  The first sentence is true and the second sentence is false 
D)  The first sentence is false and the second sentence is true

Question 8

Ion exchange chromatography
I. separates proteins from a mixture based on each protein's isoelectric point
II. depends on the pH at which a protein is electronically neutral
III. depends on the pH at which the positively charged residues of a protein
Equal the negatively charged residues
IV. uses coulombic effects to separate proteins

Accepted Answer

A)  I only 
B)  I and II 
C)  IV only 
D)  I, II and IV 
E)  I, II, III and IV

Question 9

One problem with producing biologics in cells that differ from human cells is that proteins may be alternately ___, which could affect purification and/or function of the ultimate pharmaceutical.

Accepted Answer

A)  phosphorylated 
B)  glycosylated 
C)  cleaved 
D)  processed 
E)  All of the above

Question 10

The hydrodynamic radius may complicate the planned elution of a protein of a particular MW in that

Accepted Answer

A)  a protein with spherical shape may elute later than expected from a column packed with 25-50 size beads 
B)  a protein with a prolate shape may elute later than expected from a column packed with 25-50 size beads 
C)  a protein with a prolate shape may elute earlier than expected from a column packed with 25-50 size beads 
D)  a protein with oblate shape may elute earlier than expected from a column packed with 1200 size beads 
E)  Both A and B

Question 11

London dispersion forces, a type of van der Waals interaction, are much weaker than hydrogen bonds. The strength of London dispersion forces varies with the inverse square of the distance between two charged species held within a molecule.

Accepted Answer

A)  Both sentences are true 
B)  Both sentences are false 
C)  The first sentence is true and the second sentence is false 
D)  The first sentence is false and the second sentence is true

Question 12

Carboxymethyl (CM) ion-exchange resin

Accepted Answer

A)  bears a positive charge 
B)  contains amino groups, including newer quarternary amines 
C)  is termed an anion-exchange resin 
D)  binds proteins relatively weakly due to their low charge density 
E)  None of the above

Question 13

Hydrogen bonds are strongest when

Accepted Answer

A)  an electropositive atom is attracted to a polarized hydrogen attached to -OH or -NH 
B)  an electronegative atom is attracted to a polarized hydrogen attached to a phenyl group 
C)  all groups are arranged in a linear fashion 
D)  a bond length of 50 angstroms can be made 
E)  All of the above

Question 14

A C-8 column would preferentially bind

Accepted Answer

A)  strongly hydrophobic proteins 
B)  proteins enriched in tyrosine and phenylalanine 
C)  negatively charged proteins 
D)  proteins with low MW 
E)  Both A and B

Question 15

Ultrafiltration is a combination of

Accepted Answer

A)  ion-exchange and size-exclusion chromatography 
B)  ion-exchange chromatography and centrifugation 
C)  size-exclusion chromatography and centrifugation 
D)  dialysis and centrifugation 
E)  size-exclusion chromatography and dialysis

Question 16

A biotinylated protein likely will not be denatured or modified too drastically, so may be reintroduced to a cell. If the biotinylated protein binds other cellular molecules, avidin may be used to purify the biotinylated protein paired to its partner.

Accepted Answer

A)  Both sentences are true 
B)  Both sentences are false 
C)  The first sentence is true and the second sentence is false 
D)  The first sentence is false and the second sentence is true

Question 17

Which is NOT true of a cellular protein with an acidic isoelectric point?

Accepted Answer

A)  Its pI (isoelectric point) is likely at pH 1 or 2 
B)  It contains more anionic amino acid residues than cationic amino acid residues 
C)  At neutral pH, its carboxyl groups would be deprotonated 
D)  It would bind to a positively charged ion-exchange resin 
E)  It would be best to use an anion exchange resin to separate this cellular protein

Exam 21: Biomolecule Purification

Which is NOT important to size-exclusion chromatography?

A researcher adds a "tag" of several histidine residues to an engineered protein in order to purify the protein using

Large quantities of proteins may be isolated from

A typical protein purification plan might maximally enrich a sample ___ fold above that found in the original cell lysate.

If a protein binds a specific ligand

To yield sufficient biologics, pharmaceutical companies use _ to grow sufficient cells, commonly with __ versions of natural proteins.

In size exclusion chromatography, resins with small pore sizes will be able to resolve large molecules but not small ones. Therefore, the size of the pore must be matched to the estimated size of the protein to be purified.

One problem with producing biologics in cells that differ from human cells is that proteins may be alternately ___, which could affect purification and/or function of the ultimate pharmaceutical.

The hydrodynamic radius may complicate the planned elution of a protein of a particular MW in that

London dispersion forces, a type of van der Waals interaction, are much weaker than hydrogen bonds. The strength of London dispersion forces varies with the inverse square of the distance between two charged species held within a molecule.

Carboxymethyl (CM) ion-exchange resin

Hydrogen bonds are strongest when

A C-8 column would preferentially bind

Ultrafiltration is a combination of

A biotinylated protein likely will not be denatured or modified too drastically, so may be reintroduced to a cell. If the biotinylated protein binds other cellular molecules, avidin may be used to purify the biotinylated protein paired to its partner.

Which is NOT true of a cellular protein with an acidic isoelectric point?