1.Stephen purified an enzyme from a crude lysate solution. The specific activity

Question

1.Stephen purified an enzyme from a crude lysate solution. The specific activity of the crude lysate was 3 U mg-1. The first step of his purification was anion-exchange chromatography, and after this step the specific activity was 6 U mg-1. What is the relative purity of the preparation after the anion-exchange chromatography (to 2 s.f.)?

2.Michael measured the protein concentration of a sample using the method of Bradford, and found it to be 8 µg mL-1. The sample he used for the measurement was 5000× diluted. What was the concentration of the original (undiluted) sample (in mg mL-1 to 2 s.f.)?

3.

During a multi-step purification protocol, what would you expect to happen to the total pyruvate kinase activity at each step?

Select one:

a. Increase

b. Stay the same

c. Decrease

Explanation / Answer

Specific activity of crude lysate :   3 U mg-1

Specific activity of purified lysate : 6 U mg-1

Relative purity = Specific activity of purified lysate / Specific activity of crude lysate

= 6 U mg-1 / 3 U mg-1

= 2

2) Protein concentration using bradford : 8 µg mL-1

This protein sample was 5000 times diluted. Therefore original concentration of protein is 8 µg mL-1 x 5000 = 40000 µg mL-1 = 40 x 103 x 10-6 g ml-1 = 40 x 103-6 g ml-1 = 40 x 10-3 g ml-1 = 40 mg ml-1

3) Total pyruvate kinase activity will decrease at each step because protein is lost at each step.

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.