Question

Protein purification is usually done in a number of steps, often using multiple methods. Why do you think this is the case?

Answer 1

There are three main reasons for protein purification to be an extensive process -

1. The first reason is that we have to purify all the protein present in a cell from all other by molecules like nucleic acid, lipids and carbohydrates which are also present in the cell. By doing so, we get complete protein content of the cell which is called as the proteome of a cell.

2. The proteome of a cell is itself a huge content of proteins. Just think about the number and types of proteins present in a cell and you would be surprised by the number of proteins in a Cell. All the enzymes are protein in nature. All the Transporters protein in nature. And there are structural proteins like actin and myosin as well. So to separate the protein of our choice from such a big content is very difficult.

3. The difficulty lies because of the sensitivity of protein structure towards changes in its chemical environment. Any change in temperature or pH or salt concentration or any chemical that disrupt protein structure is detrimental to the protein and therefore its function. If we end up having such type of protein, then it would be of no used to us. Protein which is not in its native structure, wont allow us to study it's function.

So every step of protein purification is extensively laborious and requires to maintain optimum chemical conditions for the protein to remain and its native structure.

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