[Todos] Fwd: CHARLA IFLYSIB: Martes 6/12 - 11:30 hs - Macromolecular structure refinement with chemical accuracy using quantum chemistry tools.

Vie Dic 2 11:11:52 ART 2016

-------- Mensaje original -------- 

 		ASUNTO:
 		CHARLA IFLYSIB: Martes 6/12 - 11:30 hs - Macromolecular structure
refinement with chemical accuracy using quantum chemistry tools.

 		FECHA:
 		2016-12-02 11:06

 		REMITENTE:
 		Charlas Iflysib <charlas.iflysib at gmail.com>

 		DESTINATARIO:
 		academic at fcaglp.unlp.edu.ar, fcnym at museo.fcnym.unlp.edu.ar,
info at ciop.unlp.edu.ar, internet at biol.unlp.edu.ar, scyt at frlp.utn.edu.ar,
secre2 at fisica.unlp.edu.ar, secre at biol.unlp.edu.ar,
secre at mate.unlp.edu.ar, secretaria at inifta.unlp.edu.ar

Estimados: 

Agradecemos la difusión de la próxima charla del IFLYSIB. 

La comisión Chifly. 

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Hola a tod at s, 
l at s invitamos a la próxima charla del iflysib a realizarse el día martes
6/12 a las 11:30 hs.  En esta oportunidad, Raul Cachau (Frederick
National Laboratory for Cancer Research) nos va hablar sobre: 

Macromolecular structure refinement with chemical accuracy using quantum
chemistry tools

L at s esperamos con toda la buena onda 😊!  

IFLYSIB (Instituto de Física de Líquidos y Sistemas Biológicos) 
Calle 59, 789 entre 10 y 11 

Comisión Chifly 

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MACROMOLECULAR STRUCTURE REFINEMENT WITH CHEMICAL ACCURACY USING QUANTUM
CHEMISTRY TOOLS 

Raul E. Cachau 

Frederick National Laboratory for Cancer Research, Frederick, Maryland
and Bowie State University, Bowie, Maryland, USA

The Protein Data Bank (PDB) total number of entries at resolution better
than 1A now total 722, 355 of which belong to systems with molecular
weight greater than 20kD. Our recent analysis of a large set of
structures refined at sub-atomic to medium resolutions suggests the
chemical accuracy threshold to be ~0.85A resolution and is obtainable in
favorable cases only. 

The overall quality of the structures rapidly decays at lower
resolutions with a fast accumulation of chemical artifacts at
resolutions > 1.25A. Many errors can be attributed to the qualitative
restrains used in the refinement protocols. 

I will discuss some of the common artifacts observed, and the results
recently obtained using QM/X-ray refinement protocols including the
first macromolecular structure solved using a QM restraint without the
application of a divide and conquer simplification (Chitinase
PDBID:4WKA; PMID: 26143917) using our program QMRx. 

Our results suggest chemical accuracy could be extended to the 1.25A
-1.5A resolution range in favorable cases, especially when combined with
high precision mass spectrometry data. The application of linear scaling
full SCF approaches may further help elucidate previously unrecognized
long distance couplings within the macromolecular structure as well
(PMID: 24573500). 

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