Q: Saporin (Cat. #PR-01) has been shown to enzymatically inhibit the function of the ribosome, which follows that protein synthesis is then inhibited. Inhibition of protein synthesis brings about “cell death” to my knowledge. To detect “cell death” usually does not take a longer time to detect than “growth inhibition,” I suppose. So what I would like to ask you is: “at least” how many hours will it take to detect “cell death” caused by saporin. In your protocol, the recommended duration of assay is 72 hours. Does that duration contain much allowance? Of course, the duration must be dependent on the speed (or efficiency) of internalization of saporin, I understand. But once saporin is internalized, how many hours (or minutes) will it take to kill the target cell?
A: 72 hours is for the great majority of cell lines, but there are a very few that require 48 hours and a very few that require 96 hours (maybe 1 of each of the 100 or so that we’ve tried). The variation in time from 72 hours is not much on the shorter side, but is only limited by the few living cells proliferating on the longer side.
It is easy to see dead cells in the microscope, so you may want to visually check your cells at different times to verify that 72 hours is correct.
How many hours will it take after internalization to kill a cell? Quite a few, because there are several processes that need to occur: the enzyme must inactivate a sufficient number of ribosomes to inhibit protein synthesis, and then the cell has to stop living because of the turnover and loss of those proteins. That takes time.
Related: Saporin (Cat. #PR-01)