shelf life of PMSF/ leupeptin in buffer - (Aug/15/2005 )

hi, last week i had made lysis buffer with PMSF (2 ml 20 mM in EtOH), leupeptin and protease inhibitor cocktail for a previous protein prep. i have some left over and am wondering if it would still be good for use this week for another protein prep. i could make fresh, but i have run out of protease inhibitor cocktail and leupeptin and am wondering what to do...

thanks..

hi
i don't know for leupeptin.
For your protease cocktail, it depends of its composition. But for PMSF, half life in aqueous solution is 30'. So i wouldn't use the remaining solution at all.
Fred