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have my protein coagulated at -20? - very strange thing happening... (Feb/09/2006 )

hello again im having really strange problem....i expressed my protein in E coli and I check it on SDS-PAGE and it seems to be i keep it at -20 for 2 days and decide to check it by western (it is bolied and kept in 1xSDS loading buffer)....i take it from -20 and want to load it on the gel and there is some white sticky cloud inside it... blink.gif i swear it wasnt there 2 days i only take the soluble portion...and now im running the gel...but im worrying what was it? can my protein be there? could proteins coagulate somehow by freezing???? please explain this to me... unsure.gif

N.B. non induced tube (0 hour IPTG) had no cloud...



does it go away if you warm a little bit?

another thing, if you do a BCA of the 'soluble' portion do your numbers change?


I didnt do BCA from the beginning.... ph34r.gif ....just ran positive control to estimate how much protein.....and I boiled the samples another time for 3 minutes before loading but it didnt go away... unsure.gif