Question

Why hypotonic solution kcl is used in protein isolation?

Answer 1

the context of nucleus, osmotic pressure is not really relevant, as the nuclear pores are huge."  it might be that we ought not take into consideration tonicity issues... but 0.3 M Sucrose will increase osmolarity of the solution at least with + 300 mosmol.  this will add considerably to hyperosmolarity of the whole lysis buffer solution (not to forget: The common isotonic buffer used in DNA isolation is buffered sucrose). 

Answer 2

A lysis buffer is a buffer solution used for the purpose of breaking open cells for ... For lysis buffers targeted at protein extraction, protease inhibitors are often included, and in difficult cases .

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