On Wed, Jan 16, 2013 at 2:53 PM, Roger Rowlett <[log in to unmask]> wrote:
> When you are a building a metalloenzyme model you should really have some
> solid evidence that a metal ion is present by (1) inclusion in the
> crystallization medium, (2) direct determination by an analytical technique,
> (3) UV-visible spectroscopy (when appropriate--obviously Zn(II) is d10 and
> silent in the visible d-d transition wavelength range) and/or (4)
> appropriate coordination geometry and bond lengths.
What about: (5) anomalous scattering (i.e. anomalous difference map)?
Even on a home source I suspect Zn should still be visible, and at
shorter wavelengths this should certainly be the case if the anomalous
data are reasonably good and complete. The coordination geometry and
bond lengths aren't necessarily going to be definitive at this
resolution, although I agree that it should be approximately
tetrahedral.
-Nat
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