True/False Question: Side chain of a serine residue in the active site of an enzyme can serve as a nucleophile during the catalysis. O True O False

Can you please solve the following question, both parts please.

200 ml of a 2% protein solution containing an enzyme that you want to purify. Half of the sample is subjected to method A, consisting of fractionated precipitations and 5 ml of final solution are obtained, with a concentration protein equal to 5 mg / ml and enzymatic activity equal to 2000 U / ml. The other half is subjected to method B, consisting of ion exchange chromatography, and a final solution of 10 ml, with protein richness equal to 10 mg / ml and with an activity enzymatic also equal to 2000 U / ml. You want to know: a) Which of the two methods has provided the purest enzyme. b) By which of the methods the greatest amount of enzyme has been obtained.

Define the word "enzyme inhibition."