I would like to know that how can we take low or precise number of cells from a cell lysate? (without using any protein quantification assay).

Let say, If I have a cell line having cell density 5x10^5 cells/mL (and its avg amount of protein concentration is 0.1ng/cell)

If I lyse these cells at the concentration of 5x10^5 cell/mL with buffer (eg., 0.1% rapigest + 10mM DTT). After achieving cell lysate, how can I take precise cell numbers from this lysate for further sample processing (e.g, alkylation, digestion etc)?

For eg., if I want to have 100cells/5ul or 1000cells/50ul , then how can I take it from cell lysate?

I know I'll have to dilute my lysate, but I'm bit confused how to achieve that based on cell concentration? how much lysis buffer and dilution would be appropriate?

Note: In my case I can't use any protein quantification assay for measuring protein concentration.

I would highly appreciate if anyone can help please.

Looking forward to hear soon.


  • $\begingroup$ As @Price mentioned, it doesn't make sense to talk about number of cells in a lysate. Lysis breaks the cell membranes, so there are no cells after lysis. Are you trying to determine how much volume of lysate represents the contents of N cells? $\endgroup$ – divibisan Dec 21 '18 at 23:54