Some time you need to include detergent & or sonication, to get the lysis of the cell. I think you should have a look at Methods of Enzymology No 1 & No.20 as well as No. 22 . You will find details about how you treat your samples to extract different proteins from different types of cells.''( animal cell ,plant cell & bacterial cells).

Good luck.

Greetings,

If you are using sonicator, add 3% SDS or some other mild detergent, that could work as an aid for cell lysis. There several lysis buffer described in scientific literature that could work for your needs, however, you have to try them yourself to see if they actually yields the kind of results you need. If gel analysis is all you need, you could even try TRIzol, as it happens to have a very Good cell lytic effect. However, If you are planning to perform enzymatic activity assay, try to use a buffer that has proper composition, being these TRIS.HCl, phosphates, maybe EDTA, so the proteins stay in solution and precipitate because of denaturing factors.

Best regards