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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?
thanks

-yobou-

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.

-mdfenko-

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: http://www.pubmedcentral.nih.gov/articlere...bmedid=19425170
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)?
thanks

-yobou-

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.

-mdfenko-