4. PMSF (phenylmethylsulfonyl fluoride) is an inactivator of serine proteases. I

Question

4. PMSF (phenylmethylsulfonyl fluoride) is an inactivator of serine proteases. It is commonly used in the production of protein for experimental study, it prevents cellular proteases from digesting the protein of interest. The structure of PMSF is: Starting with the framework of a serine protease active site provided below, show a complete curved arrow mechanism for how PMSF inactivates the enzyme. In your drawing, also complete the missing portions of the enzyme, and show all important interactions in the active site. Draw any H-bonds as dotted lines. a. b. PMSF is a (choose all that apply): i. Transition state analog ii. Substrate analog ili. Product analog iv. Competitive inhibitor v. Uncompeititive inhibitor vi. Mixed inhibitor True or false? Lowering the pH of the solution would alter binding by PMSF. In a single sentence, explain how you arrived at your answer c.

Explanation / Answer

a. To make the study more easy PMSF being a serine protease inhibitor

Enzyme(active site)Ser-O-H + F-SO2CH2C6H5 ? EnzymeSer-O-SO2CH2C6H5 + HF

Serine protease + PMSF ? Irreversible enzyme-PMS complex + HF. The enzyme complex is an irreversible one and prevents the activity of Serine protease. Hydrogen bonds are formed between O-H group and sulfur/oxygen group.

b.PMSF is a competitive inhibitor

c. PMSF has an optimal activity at a pH range of 6-8 below which or above the activity goes down, hence binding also is affected. The answer is true. As serine has pI of 7 , a pH of less than 7 would lead to formation of positively charged ion which would bind differentially with PMSF at low pH. The binding may become stronger due to positive and negative charge interaction of PMSF and Serine in serine protease

Related Questions

Navigate

• Browse (All)
• Browse 4
• Subjects

---

---

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