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precipitation of pepstatin A - (Jul/02/2009 )

Dear all
when I add different concentrations of pepstatin A (10, 25, 50 microM final, stock was dissolved in DMSO) to DMEM it is precipitated and shaking the culture dish does not help. any recommendation?


we always make up our pepstatin in methanol.

most of the literature from the suppliers recommend methanol or ethanol (sigma is the only company i found that mentions dmso).

the companies say that the working concentration range is 0.5-1 ug/ml (sigma says 1uM). you may be trying to put too much in to your medium.


thanks mdfenko, but according to sigma data sheet they mentioned that (At 25 mg/mL DMSO Pepstatin A forms a clear, faint yellow solution). So do I have to purchase a new one?
As for the concentration used according to this paper:
they used pepstatin A at 10 μg/ml final. and in another cancer research paper they used 100 microM concentration final. Do you use it to inhibit cell death or inhibit autophagy (in combination with E64D)?


we were using pepstatin, at 1ug/ml , as part of an inhibitor panel for the proteases with which we worked.

i don't know if you have to buy more (did you solubilize the whole thing?). i would.

you could try to slowly increase the concentration of pepstatin in your medium.