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Hi, There's nothing wrong with trying to crystallize something that has 1M imidazole in it. However, if things do not work out then removing the imidazole (via an additional purification step, or simply by dialysis or desalting, sizing, etc.) is one of the next logical steps to try. In at least one case in my personal experience, I was only able to obtain decent crystals after adding 0.6M imidazole/acetate buffer to the crystallization set-up. Two imidazole molecules were later found in the structure, occupying 'greasy spots' on the protein surface. Other folks that already answered this request all had excellent points to make. My own two cents in this case would be that during the development of a purification protocol speed and number of steps are two (of several) very important parameters. On the one hand sometimes it is better to leave trace impurities in, and store the protein once it is 'essentially pure', rather than beat one's head against cement trying to remove the last clinging impurities, only to discover that the pure protein is compromised or that there's not enough left due to losses in process. On the other hand, people will readily share horror stories about how proteins only would crystallize for them once the purity exceeded a magical percentage, or once a specific pesky impurity was removed, a magical purification step was added, etc. Therefore, it is best to go with the protein and figure things out practically :) Artem PGP On Wed, 2005-09-14 at 14:53 +0200, Nada wrote: > Hello. > > Please I would like to know if someone has had some experience with > crystallization of protein in solution containing also 1M imidazole. > Is it necessary to remove it from solution after elution of protein > from Ni-column? > > Thank you > > Nada Pavlendova > > IMB, Bratislava, Slovakia > >
