1. Pick the odd one out.
a) Carboxymethyl (CM)
b) Diethylaminoethyl (DEAE)
c) Sulphopropyl (SP)
d) Methyl sulphonate (S)
Explanation: The odd one out is diethylaminoethyl (DEAE) as it is an anion exchanger as compared to Carboxymethyl (CM), sulphopropyl (SP) and methyl sulphonate (S) are cation exchangers. Cation exchangers are negatively charged exchangers which have positively charged counter ions (cation).
2. Peroxidases can be purified using ___________
a) gel filtration
b) cation exchanger
c) anion exchanger
d) affinity chromatography
Explanation: Peroxidases can be purified using anion exchanger which has Q-sepharose column and the sample is eluted with NaCl gradient of 0.35, 0.4, 0.45 and 0.5 M in Tris-HCl buffer. Cytochrome c is purified by using cation exchanger. Alpha amylase is purified by using gel filtration technique. Acetylcholine esterase is purified by using affinity chromatography.
3. Alkaline protease is purified by using ________
a) DEAE-cellulose
b) Q-sepharose
c) Amberlite CG-50
d) Sephacryl S-300
Explanation: Alkaline protease is purified by using DEAE-cellulose which has been equilibrate with 10 mM Tris/ HCl buffer, containing 50 mM KCl. Q-sepharose is used to purify peroxidases. Amberlite CG-50 is used to purify cytochrome c. Sephacryl S-300 is used to purify alpha amylase by the gel permeation technique.
4. Cation exchange resin is used to purify __________
a) alkaline protease
b) peroxidase
c) alpha amylase
d) cytochrome c
Explanation: Cation exchange resin prepared using amberlite CG-50 is used to purify cytochrome c. Alkaline protease and peroxidase are purified by using anion exchangers. Alpha amylase is purified by using a gel filtration technique using Sephacryl S-300.
5. Which of the functional groups are not present in cation exchangers?
a) SO3–
b) OPO3–
c) NR3+
d) COO–
Explanation: NR3+ is functional group present in anion exchangers. Cation exchangers have anionic functional groups such as SO3–, OPO3– and COO–.
6. The chromatographic method of separating biochemical mixture of compounds, based on highly specific biological interactions is referred to as ______________
a) thin layer chromatography
b) ion-exchange chromatography
c) affinity chromatography
d) gel permeation chromatography
Explanation: Affinity chromatography is a method based on separation of molecules based on specific biological interaction such as antigen-antibody, enzyme-substrate etc. Thin layer chromatography is a technique which separates molecule based on their solubility in stationary or mobile phase. Ion-exchange chromatography is a technique based on separation of molecules using the ions present in them. Gel permeation chromatography is based on separation of molecules based on their size.
7. Which of the following is not a highly specific biological interaction to be used in affinity chromatography?
a) Cations-anions
b) Antigen-antibody
c) Enzyme-substrate
d) Receptor-ligand
Explanation: Cations-anions are used in ion-exchange chromatography to separate molecules based on the ions present in them. Antigen-antibody, enzyme-substrate, receptor-ligand are used in affinity chromatography to separate highly specific biological interactions molecules.
8. Which of this is not true while selecting a solid matrix or column during affinity chromatography?
a) The matrix should interact weakly with enzymes
b) The matrix should be based on inorganic compounds
c) The matrix should exhibit good flow property
d) The matrix should be highly porous
Explanation: The matrix should be based on inorganic compounds is true in case of ion-exchange chromatography. The following are true in case of matrix selection during affinity chromatography.
• The matrix should interact weakly with enzymes in order to minimize non-specific adsorption of other enzymes.
• The matrix should exhibit good flow property.
• The matrix should be highly porous when there is relatively weak affinity between the ligand and protein.
• The matrix should be chemically and mechanically stable.
• The matrix must possess certain chemical groups.
9. In affinity chromatography, the matrix should be chemically and mechanically stable.
a) true
b) False
Explanation: In affinity chromatography, the matrix selected should be chemically and mechanically stable because of coupling conditions and varying conditions pH, ionic strength, temperature and presence of denaturants which may be needed for adsorption or elution. Due to this, it permits the repeated use of certain specific adsorbents. Hence the above statement is true.
10. The matrix selected during affinity chromatography must possess certain chemical groups.
a) true
b) false
Explanation: In affinity chromatography, the matrix must possess certain chemical groups which can be activated or modified in order to allow the chemical linkage of variety of ligands under conditions which are harmful to the matrix. Hence the above statement is true.