Crystals are supposed to be red if you have oxidized iron in the heme and deep pink/scarlet if the iron is reduced.

If you removed the iron (for example EDTA during purification) or substituted with something during purification or crystallization, you could loose the color.

It is trivial to check your crystals on the synchrotron beamline with fluorescence spectrum and "see" which metals are there.

Cheers,

Nukri

Ruslan Sanishvili (Nukri), Ph.D.

GM/CA-CAT, Bld. 436, D007
Biosciences Division, ANL
9700 S. Cass Ave.
Argonne, IL 60439

Tel: (630)252-0665
Fax: (630)252-0667
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From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of Jan Schoepe
Sent: Wednesday, March 12, 2008 2:49 PM
To: [log in to unmask]
Subject: [ccp4bb] Color of heme containing Xtals

Hello everybody,

I wonder if anybody has experience with heme (or to be more precise: heme b) containing proteins which Xtals do not look red under the microscope. How might the technique for crystallization (e.g. sitting drop, hanging drop) influence the intensity of the color? Many thanks!

Jan

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