551. The unfolding of regular secondary structure causes
A. little increase in the entropy of protein
B. large decrease in the entropy of the protein
C. no change in the entropy of the protein
D. large increase in the entropy of the protein

552. During successful purification scheme, this may be expected that the
A. specific activity increases
B. specific activity decreases
C. number of proteins in the sample decreases
D. both (a) and (c)

553. In ion-exchange chromatography
A. proteins are separated on the basis of their net charge
B. proteins are separated on the basis of their size
C. proteins are separated on the basis of their shape
D. either (b) or (c)

554. Which of the following may be added to stabilize the protein after yeast cells disruption?
A. NaCl
B. Protease inhibitor
C. AMP
D. All of these

555. Gel-filtration chromatography separates on the basis of
A. size and shape using porous beads packed in a column
B. size using porous beads packed in a column
C. shape using porous beads packed in a column
D. none of the above

556. Affinity chromatography deals with the
A. specific binding of a protein constituents for another molecule
B. protein – protein interaction
C. protein – carbohydrate interaction
D. none of the above

557. A purified protein sample contains 10 μg of protein and has an enzyme activity of 1 m mole of ATP synthesized/sec (1 unit). What is the specific activity of the final purified sample?
A. 1,000 units/mg
B. 10,000 units/mg.
C. 100,000 units/mg
D. 1,000,000 units/mg

558. Proteins separation can be carried out on the basis of
A. net charge
B. solubility in salt solutions
C. size or mass
D. all of these

559. The best way to determine the location of protein in the purification scheme is to measure the
A. rate of ATP synthesis
B. changes in the refractive index
C. UV absorption
D. mass spectroscopy of the protein

560. The conformational changes from the T to the R state is initiated by
A. binding of oxygen to the heme
B. movement of the proximal histidine towards the heme
C. movement of the F-helix, which contains the proximal His
D. reorganization of protein-protein contacts between the individual subunits

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