Hi Ed,
Chapter 18.3 of international tables vol F includes values designated
EH99 which are from a more recent CSD release than the original 1991
Engh & Huber paper.
R. A. Engh and R. Huber. Structure quality and target parameters.
International Tables for Crystallography (2012). Vol. F, ch. 18.3, pp. 474-484
doi: 10.1107/97809553602060000857
http://it.iucr.org/Fb/ch18o3v0001/
Also, the Buster groups' Grade server provides dynamic use of
the CSD database to derive restraints. http://grade.globalphasing.org
And the PURY restraint database has restraints derived from recent CSD
releases. I belive it requires a current CSD license is required for use.
http://pury.ijs.si/
Regards,
Mitch
-----Original Message-----
From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of Ed Pozharski
Sent: Monday, January 14, 2013 9:55 AM
To: [log in to unmask]
Subject: [ccp4bb] engh huber
To what extent "modern" geometric restraints have been upgraded over
original Engh&Huber? And where I can find a consensus set of values
(with variances)?
For example, Fisher et al., Acta D68:800 discusses how histidine angles
change with protonation, and refers to Engh&Huber when it says that
ND1-CE1-NE2 goes from 111.2 to 107.5 when histidine acquires positive
charge (Fig.6). But angle table (Table 3) in original Engh&Huber from
1991 does not have any 107.5 value and seems to suggest that the numbers
should rather be 111.7+-1.3 and 108.4+-1.0, respectively.
I understand that these values are derived from structural databases and
thus can be frequently updated. Is there some resource where "most
current" values would be listed?
Cheers,
Ed.
--
After much deep and profound brain things inside my head,
I have decided to thank you for bringing peace to our home.
Julian, King of Lemurs
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