Enzyme Technology Multiple Choice Questions on “Enzyme Preparation for Sale”.
1. Which of these is of primary importance to the enzyme producer and customer?
A. pH
B. Temperature
C. Denaturation time
D. Activity
Answer: D
Clarification: Enzymes are sold on the basis of overall activity and hence it of prime importance to the enzyme producer and customer. Usually, the freshly prepared enzyme will have higher activity so that the enzyme preparation will have guaranteed storage life. The storage conditions and expected rate of loss of activity for a particular enzyme is given by the manufacturer. Hence it is important the customers follow the instruction by the manufacturer so that the enzyme activity may be retained during storage and use.
2. ____________ is an art and is a method used to stabilize enzyme preparations.
A. Chromatography
B. Centrifugation
C. Formulation
D. Filtration
Answer: C
Clarification: Formulation is an art and a method used to stabilize enzyme preparations. These are kept secret and revealed to customers only under confidential agreement. This is the only thing that gives a manufacturer the competitive edge over rival companies.
3. Which of the following approach is not a key to maintaining enzyme activity?
A. Use of additives
B. Controlled used of covalent modification
C. Accurate, precise, reproducible, linear and free from electrical noise
D. Enzyme immobilization
Answer: C
Clarification: “The response should be accurate, precise, reproducible, linear and free from electrical noise” is a beneficial feature of biosensor. The key to maintaining enzyme activity is the maintenance of conformation which means to prevent unfolding, aggregation and changes in the covalent structure. Three approaches which are used are:
• Use of additives.
• Controlled used of covalent modification.
• Enzyme immobilization.
4. Which of these is used for enzyme stabilization?
A. Potassium hydrogen phosphate
B. Sodium thiosulphate
C. Calcium chloride
D. EDTA
Answer: A
Clarification: Potassium hydrogen phosphate and ammonium sulphate are powerful enzyme stabilizers, whereas sodium thiosulphate, calcium chloride and EDTA are enzyme destabilizers. For water molecules, the salts and proteins are competing with each other. These salts binds to charged groups which result in interaction between hydrophobic areas of enzymes. Thus making it more resistant to thermal folding. Some salts are much more effective in destabilization than stabilization which disrupts the structure of water locally.
5. Pick the odd one out.
A. Glycerol
B. Polyvinyl alcohol
C. Sorbitol
D. Mannitol
Answer: B
Clarification: Polyvinyl alcohol is a hydrophilic polymer that is used to stabilize enzymes. Whereas glycerol, sorbitol and mannitol are low molecular weight polyols which stabilize enzymes in the following way:
• By repressing microbial growth due to the reduction in the water activity.
• Formation of protective shells which prevent unfolding processes.
6. Which of these is not a hydrophilic polymer used to stabilize enzymes?
A. Polyvinyl alcohol
B. Polyvinylpyrrolidone
C. Mannitol
D. Hydroxypropylcelluloses
Answer: C
Clarification: Mannitol is a low molecular weight polyol that is used to stabilize enzymes. Polyvinyl alcohol, polyvinylpyrrolidone and hydroxypropylcelluloses are hydrophilic polymers which stabilize enzymes in the following ways:
• A process of compartmentalization wherein the enzyme-enzyme and enzyme-water interactions are replaced by less potentially denaturing enzyme-polymer interactions.
• By stabilizing the hydrophobic effect within the enzymes.
• By specific chemical modifications of amino acid side chains are possible which may result in stabilization.
7. Which of these is not added as a preservative for solid enzyme preparation?
A. Thiols
B. Starch
C. Lactose
D. Carboxymethylcellulose
Answer: A
Clarification: Thiols are used as preservatives in liquid enzyme preparations to create a reducing environment. Enzymes are very much more stable in the dry state than in solution. Solid enzyme preparations sometimes consist of freeze-dried protein with inert materials such as starch, lactose, carboxymethylcellulose and other poly-electrolytes that protect the enzyme during a cheaper spray-drying stage.
8. Which of the following is not added as a preservative for liquid enzyme preparation?
A. Antibiotic
B. Benzoic acid esters
C. Thiols
D. Carboxymethylcellulose
Answer: D
Clarification: Carboxymethylcellulose is an inert material used as preservatives in solid preparations. Substrates, thiols, antibiotics, benzoic acid esters, inhibitors of contaminating enzyme activities and chelating agents are used as preservatives for liquid enzyme preparations. These additives must be compatible with the final use of the enzyme’s product.