# Enzyme Technology Questions and Answers – Recent Advances – Use of Aqueous 2 Phase Systems

This set of Enzyme Technology Multiple Choice Questions & Answers (MCQs) focuses on “Recent Advances – Use of Aqueous 2 Phase Systems”.

1. In 1896, a two-phase aqueous system was first time noted by ________
a) Miachelis and Menten
b) Darwin
c) Koshland
d) Beijerinck

Explanation: In 1896, a two-phase aqueous system was first time noted by Beijerinck. In this case, two phases were formed when agar was mixed with soluble starch or gelatin. Miachelis and Menten studied enzyme kinetics. Darwin studied the theory of evolution. Koshland produced an induced fit model.

2. The most thoroughly investigated two-phase aqueous system is ___________ system.
a) potassium phosphate buffer-polyethylene glycol
b) agar-starch
c) dextran-polyethylene glycol
d) sodium carbonate-polyethylene glycol

Explanation: The most thoroughly investigated two-phase aqueous system is dextran-polyethylene glycol system. In this system, dextran forms the more hydrophilic, denser, lower phase and polyethylene glycol the more hydrophobic, less dense, upper phase. In potassium phosphate buffer-polyethylene glycol system, the polymers form the upper hydrophobic phase. Agar-starch was noted as a two-phase system for the first time by Beijerinck in 1896. Sodium carbonate- polyethylene glycol is another such system used during downstream processing mainly in biotechnological and chemical industries.

3. Aqueous-two phase systems are of considerable value to biotechnology.
a) True
b) False

Explanation: The statement “Aqueous-two phase systems are of considerable value to biotechnology” is true because of the following reasons:
* Aqueous-two phase systems provide rapid separation of biological materials with little probability of denaturation.
* Aqueous-two phase systems provide efficient mixing under very gentle stirring and rapid partition.
* Aqueous-two phase systems separate compounds in a few minutes, minimizing the harmful action of endogenous proteases.

4. Which of the following is not a use of aqueous-two phase system?
a) Enzyme kinetics
b) Separation of different types of cell membranes
c) Purification of enzymes
d) Extractive bioconversions

Explanation: Aqueous-two phase system have been used successfully in the following areas:
* Separation of different types of cell membranes.
* Separation of different types of organelles.
* Separation and purification of enzymes.
* Extractive bioconversions.
Enzyme kinetics study cannot be done by using aqueous-two phase system.

5. Which of the following methodologies is not used to extract an enzyme from the upper phase of aqueous 2 phase system?
b) Desalting
d) Generating a new biphasic system

Explanation: The following methodologies are used to extract an enzyme from the upper phase of aqueous 2 phase system:
* Generating a new biphasic system
Desalting cannot be used to extract an enzyme from the upper phase.

6. Which of the following is an extractive bioconversion?
a) Aspargine to aspartate
b) Plasminogen to plasmin
c) Starch to glucose
d) Penicillin to penicilloate

Explanation: Starch to glucose using bacterial a-amylase and glucoamylase is an example for an extractive bioconversion. Starch partitions in lower, more hydrophilic, dextran-rich phase of a system comprising 3% polyethylene glycol (PEG 20,000) and 5% crude unfractionated dextran. The enzymes also partition in the bottom phase but the glucose produced distributes itself more evenly between the two phases. Glucoamylase enters the upper phase and converts any oligosaccharide entering that phase to glucose.

7. Which of this is a disadvantage of aqueous 2 phase system?
a) The enzymes which enter the upper phase are gradually lost
b) The enzymes are largely retained in homogeneous solution
c) The enzymes are stabilized by the presence of the polymers in homogeneous solution
d) No diffusion limitations to mass transfer exist

Explanation: Advantages of aqueous 2 phase system are as follows:
* The enzymes are largely retained in homogeneous solution.
* The enzymes are stabilized by the presence of the polymers in homogeneous solution.
* No diffusion limitations to mass transfer exist.
Disadvantages of aqueous 2 phase system are as follows:
* The need to separate the product from the upper phase polymers.
* The enzymes which enter the upper phase are gradually lost.

8. Which of the following is not related exponentially to partition co-efficient?
a) Surface area
b) Surface charge of the particles
c) Hydrophobicity of the phases
d) pH

Explanation: Partition coefficient may be defined as,
$$P=\frac{C_t}{C_b}$$ where Ct and Cb represent the concentrations in the top and bottom phases respectively. The partition coefficient is exponentially related to each of the following:
* Surface area.
* Surface charge of the particles.
* Difference in the electrical potential.
* hydrophobicity of the phases.
The influence of pH on protein partition is complex. A given protein distributes differently between the phases at different pH’s and ionic strength. But the presence of phosphate ions affects the partition coefficient in such way that the ions distribute themselves unequally resulting in electrostatic potential (and pH) differences. This means that systems may be ‘tuned’ to enrich an enzyme in one phase, ideally the upper phase with cell debris and unwanted enzymes in the lower phase.

Sanfoundry Global Education & Learning Series – Enzyme Technology.

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