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Home Biochemistry Protein Purification Comments

  • Question
  • A purified protein sample contains 10 ?g 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?


  • Options
  • A. 1,000 units/mg
  • B. 10,000 units/mg.
  • C. 100,000 units/mg
  • D. 1,000,000 units/mg

  • Correct Answer
  • 100,000 units/mg 


  • Protein Purification problems


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    • 1. Affinity chromatography deals with the

    • Options
    • A. specific binding of a protein constituents for another molecule
    • B. protein - protein interaction
    • C. protein - carbohydrate interaction
    • D. none of the above
    • Discuss
    • 2. Which of the following may be added to stabilize the protein after yeast cells disruption?

    • Options
    • A. NaCl
    • B. Protease inhibitor
    • C. AMP
    • D. All of these
    • Discuss
    • 3. In ion-exchange chromatography

    • Options
    • 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)
    • Discuss
    • 4. If the enthalpy change for a reaction is zero, ?G° is equal to

    • Options
    • A. T?S°
    • B. -T?S°
    • C. -?H°
    • D. lnKeq
    • Discuss
    • 5. During the unfolding reaction of a helix, breakage of each hydrogen bond requires about 2kJ/mol. This implies hydrogen bonds are

    • Options
    • A. much stronger in proteins than in water
    • B. not reformed with water
    • C. slightly weaker in proteins than in water
    • D. slightly stronger in proteins than in water
    • Discuss
    • 6. During successful purification scheme, this may be expected that the

    • Options
    • A. specific activity increases
    • B. specific activity decreases
    • C. number of proteins in the sample decreases
    • D. both (a) and (c)
    • Discuss
    • 7. Proteins separation can be carried out on the basis of

    • Options
    • A. net charge
    • B. solubility in salt solutions
    • C. size or mass
    • D. all of these
    • Discuss
    • 8. Gel-filtration chromatography separates on the basis of

    • Options
    • 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
    • Discuss
    • 9. The best way to determine the location of protein in the purification scheme is to measure the

    • Options
    • A. rate of ATP synthesis
    • B. changes in the refractive index
    • C. UV absorption
    • D. mass spectroscopy of the protein
    • Discuss
    • 10. The Hill coefficient (nH) for myoglobin and hemoglobin are respectively

    • Options
    • A. 2.8 and 1.0
    • B. 1.0 and 2.8
    • C. 1.2 and 4.5
    • D. 4.5 and 1.2
    • Discuss


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