Ho,
interesting case.
Glycerol actually forms weak complexes with metal ions:
Journal of Inorganic Biochemistry,60 299-302 (1995) and some references
therein.
But to be true, I am surprised that glycerol at concentrations of 10-15%
(?) as used in cryo conditions can compete with a metal ion binding
site in a protein. I remember I myself did titrations with Zn2+ in the
presence/absence of 5% glycerol and did not observe any effect on the
binding. There might be another effect (?) although I have no idea what
it might be.
> I am working with a metalloprotein that binds cobalt and iron. I
> was surprised that the solved structures showed the crystals
> cryoprotected with glycerol are metal free while crystals
> cryoprotected with ethylene glycol had the metals present. Both
> cryoprotectant solutions contained metal in the 10 mM range and are
> buffered at pH 9. I assume glycerol must be a weak chelator otherwise
> it wouldn't be so ubiquitous in protein biochemistry. Has anyone else
> experienced this before with glycerol?
>
>
> Ho
> UC Berkeley
>
--
***********************************
Priv.Doz.Dr. Guenter Fritz
Fachbereich Biologie
Sektion Naturwissenschaften
Universitaet Konstanz
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