Answer
Pl is the ioselectric point at this point the charge of protein will be neutral. So proteins are precipitated at this isoelectric point. Ammonium sulphate is the acidic salt, so when this ammonium suphate is dissolved in protein solution acidity will increase.
Protein solution has pH 7. so when we add ammonium sulphate to this protein solution the pH will decrease.
So when the pH reaches 5 that is isoelectric point is reached then we will get maximum precipitatiob of protein.
So ammonium sulphate is added to the protein solution untill the pH reaches 5 from 7.
Now at this pH of 5 by adding ammonium suphate we will get maximum amount of protein Q that precipitates out of the solution.
So we have to adjust the salt concentration to get pH of 5 from pH7 to maximize the amount of protein Q that precipitates out of the solution.
By salting out method the proteins are purified. By adding salt solution with the protein solution the protein will get precipitated. From the precipitate the salt added is removed by dialysis to get the pure protein. Here given to purify protein Q with some contaminant.
If there some impurities that is contaminant presentalong with protein, by salting out this contaminant also get precipitated along with protein, so the protein after precipitation also conatins that contaminant, So the protein we extracted is in impure form only not as pure protein.
Work Step by Step
Pl is the ioselectric point at this point the charge of protein will be neutral. So proteins are precipitated at this isoelectric point. Ammonium sulphate is the acidic salt, so when this ammonium suphate is dissolved in protein solution acidity will increase.
Protein solution has pH 7. so when we add ammonium sulphate to this protein solution the pH will decrease.
So when the pH reaches 5 that is isoelectric point is reached then we will get maximum precipitatiob of protein.
So ammonium sulphate is added to the protein solution untill the pH reaches 5 from 7.
Now at this pH of 5 by adding ammonium suphate we will get maximum amount of protein Q that precipitates out of the solution.
So we have to adjust the salt concentration to get pH of 5 from pH7 to maximize the amount of protein Q that precipitates out of the solution.
By salting out method the proteins are purified. By adding salt solution with the protein solution the protein will get precipitated. From the precipitate the salt added is removed by dialysis to get the pure protein. Here given to purify protein Q with some contaminant.
If there some impurities that is contaminant presentalong with protein, by salting out this contaminant also get precipitated along with protein, so the protein after precipitation also conatins that contaminant, So the protein we extracted is in impure form only not as pure protein.
