Dear Sue,
principally correct. However, without having tested it, a refinement program
might mop up the difference by lowering the B-value of a water molecule placed
instead of an Iodine. And maps at 2.9A can contain a lot of noise, too, so
that an anomalous difference map is comforting.
Cheers,
Tim
On Wednesday, January 20, 2016 03:54:18 PM Roberts, Sue A - wrote:
> The replies about how to calculate an anomalous map are helpful. But, isn't
> there an easier answer?
>
>
> I is heavy; it has 53 electrons (54 for the ion) - it has more than 3 times
> as many electrons as sulfur. The presence of a significant amount of I- at
> any site should be obvious in a difference map, at 2.9 A resolution. When
> you look at the difference peaks, if there is a reasonably occupied iodine
> site or two, they should be the largest peaks in the difference map. Even
> at 1/3 occupancy, an iodine should be discernable from water.
>
>
> Sue
>
>
> Dr. Sue A. Roberts
> Dept. of Chemistry and Biochemistry
> University of Arizona
> 1306 E. University Blvd, Tucson, AZ 85721
> Phone: 520 621 4168
> [log in to unmask]<mailto:[log in to unmask]>
>
>
> From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of rohit
> kumar
Sent: Wednesday, January 20, 2016 4:27 AM
> To: [log in to unmask]
> Subject: [ccp4bb] Iodine presence
>
> Dear All,
>
> I have a 2.9 A resolution data. Right now the R and Rfree values are 30 and
> 35 respectively without adding water.
In my crystallization condition i
> have NaI (200mM).
> How could i confirm whether iodine is present or not in my crystal??.
>
> In support, kinetic analysis suggest inhibitory effect of iodide ion on
> enzyme activity.
>
>
> Thanks
>
>
>
> --
> WITH REGARDS
> Rohit Kumar Singh
> Lab. no. 430,
> P.I. Dr. S. Gourinath,
> School of Life Sciences,
> Jawaharlal Nehru University
> New Delhi -110067
--
--
Paul Scherrer Institut
Dr. Tim Gruene
- persoenlich -
OFLC/102
CH-5232 Villigen PSI
phone: +41 (0)56 310 5297
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