> Listen, is it normal that when adding PMSF (250mM solution in MeOH)
> to cell free extract from E.coli (broked by sonication and spinned
> 12000g for 30min) to the final concentration of 0,5mM buffer becomes
> cloudly and st become to precipitate (probably protein?).
PMSF would not normally cause proteins to precipitate, but the methanol
might. That doesnt usually happen, though, because you're usually adding
such a small amount to a much larger volume of protein solution (or cell
lysate). Does it only become cloudy immediately after the addition of PMSF?