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No air in the vessel, no foam. Yield of soluble, active protein from broken cells is quite comparable or better than French press or sonication, but with no aerosols. The bead-beating unit is encased in ice water, and is used 15 s on and 45 sec off to minimize heat buildup. The solution still feels cold when transferred to centrifuge tubes for clarification. I suppose I could measure it next time to see how much it actually warms up during beating. Based on these observations, I conclude that the cell lysis by bead-beating is no more disruptive to proteins than a French press, but much, much faster. As a bonus, genomic DNA is sheared, so no more slimy lysates. We have used bead beaters exclusively since 1997 or so when I learned about them from a Swedish research group I was visiting. They are handy in both the teaching and research lab. Roger Rowlett On Oct 26, 2012 12:29 AM, "Dima Klenchin" <[log in to unmask]> wrote: > Roger Rowlett wrote: > > This goes straight into a bead beater for complete, gentle homogenization >> in 8 min. >> > > Didn't you mean "complete, foam-producing, surface denaturation-inducing" > homogenization? I am not saying that bead beater is worse than the "locally > near boiling temperatures-producing" more conventional sonication but > surely it's a stretch to call anything related to bead beater as "gentle"? > > Also, I always wondered but never seem to find an answer to: has anyone > ever measured temperature progression in a bead beater? I'd imagine that > there is a lot of heat generated - how does it compare with sonication? > (Which, at least, can be easily monitored with a thermometer in real time). > > - Dima > >