This set of Enzyme Technology Multiple Choice Questions & Answers (MCQs) focuses on “Enzymes Purification – Ion Exchange Chromatography”.
1. _____________ retains analyte molecules based on the coulombic interaction.
a) Thin layer chromatography
b) Affinity chromatography
c) Gel filtration
d) Ion exchange chromatography
Explanation: Ion-exchange chromatography retains analyte molecules based on the coulombic or ionic interaction. Gel filtration retains analyte based on the size of the molecule. Thin layer chromatography retains analyte based on the solubility of the molecules in stationary or mobile phase. Affinity chromatography retains analyte based on the affinities between 2 molecules. For example, enzyme-substrate.
2. When pH of enzyme solution is below their isoelectric point, the enzymes will be negatively charged and bind to anion exchangers.
Explanation: Enzymes possess a net charge in solution as they contain both positive and negative charges. Isoelectric point is the pH at which the net charge on the molecule is zero. When pH of the solution is reduced below the isoelectric point, the enzymes will become positively charged and bind cation exchangers. Whereas when the pH is above the isoelectric point the enzymes will become negatively charged and bind to anion exchangers. Hence the above statement is false.
3. Cation exchange chromatography retains positively charged cations.
Explanation: Cation exchange chromatography retains positively charged cations as the stationary phase in the column displays negatively charged functional group such as phosphoric acid. Whereas anion exchange chromatography retains negatively charged anions as the stationary phase displays the positively charged groups. Hence the above statement is true.
4. Which of these is not an anion exchanger?
a) Diethylaminoethyl (DEAE)
b) Quaternary aminoethyl (QAE)
c) Sulphopropyl (SP)
d) Quaternary ammonium (Q)
Explanation: Anion exchangers are positively charged exchangers which have negatively charged counter ions (anions) available for exchange. Diethylaminoethyl (DEAE), quaternary aminoethyl (QAE) and quaternary ammonium (Q) are anion exchangers. Sulphopropyl (SP) is a cation exchanger.
5. 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).
6. 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.
7. Alkaline protease is purified by using ________
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.
8. Cation exchange resin is used to purify __________
a) alkaline protease
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.
9. Which of the functional groups are not present in cation exchangers?
Explanation: NR3+ is functional group present in anion exchangers. Cation exchangers have anionic functional groups such as SO3–, OPO3– and COO–.
Sanfoundry Global Education & Learning Series – Enzyme Technology.
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