> > On Mon, Jan 26, 2015 at 8:22 PM, Monica Mittal <[email protected]> > wrote: > >> Hi everyone, >> >> I need an advice on some strange thing happening to one of the protein i >> am working on. I used to purify it and set up trays and get some needle >> shaped crystals and trying seeding and other methods to optimise them. But >> recently, it stopped giving crystals even small needles. I am still >> following the same protocol with same buffer stocks. >> > By 'buffer stocks', do you also mean your stock of precipitating reagent? It's happened to me that a hit I pursued and optimized vanished when I opened a new bottle of PEG. It took too long to realize that the old PEG could have been at a higher concentration than I'd assumed, given its shelf-age. I increased the PEG % and got back the crystals.
Good luck, Emily. And not just once but since last three times it is happening. The purified >> protein in gel filtration is perfectly fine eluting at same position with >> symmetrical distribution. However when i am setting up trays under previous >> conditions, i am not getting the crystals. Instead the drops are quite >> clear. So i increased the concentration of the protein also from 8 to >> 11mg/ml, but still the same. Infact i tried adding ligand also but again no >> crystals. So i would be really grateful if anyone can give a valuable >> suggestion regarding this problem !! >> >> Thanks >> BR >> Monica >> > >
