Re: [ccp4bb] Crystallization robot and trypsin

[Bart Hazes]

On 12-01-24 08:39 AM, Regina Kettering wrote: We have a Honeybee system but do not usually use proteases.  The biggest problem we have found is that if anything precipitates in the tips they have to be washed very well, usually with water or ethanol.  The ceramic tip can be washed using low concentrations of HCl (0.1M), which I believe would also alleviate the protease problem. Regina At some point we aspirated an _expression_ plasmid, let it sit in the tip for a while and then went through different washing protocols, water, high-salt, 0.1M NaOH, and then dispense a small volume of water into a PCR reaction. We found just a water wash got rid of most of the DNA, as long as the outside of the tip was also washed. After the high salt we could no longer detect the DNA by PCR. Although protein is not the same as DNA I would have no concern about protease contamination if you implement a good wash/strip protocol for the protein dispense tip. Bart