[ccp4bb] Molecular Replacement of a Known Anomalous Substructure

- Protein crystallography

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- Protein purification
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CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: Re: twwining operator
From: Phil Jeffrey pjeffrey {- at -} PRINCETON {- dot -} EDU
Date: 2007-05-21

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Subject: unstable performance of refmac. any suggestions?
From: fang sheng wuhanwuchang {- at -} HOTMAIL {- dot -} COM
Date: 2007-05-21

Subject: Molecular Replacement of a Known Anomalous Substructure
From: Jacob_Keller j-keller2 {- at -} NORTHWESTERN {- dot -} EDU
Date: 2007-05-21

Many times when we search for anomalous scatterers, we have some a priori
info about their relative positions. For example, many proteins have
sequence-adjacent methionines, which tether the anomalous scattering
positions to certain distances. Again, there are many heavy atom derivatives
which have a known substructure, such as tungsten clusters, or even
undecagold clusters. It would seem to me that this kind of a priori info
might lend a powerful boost to heavy atom searches in noisy data.

One way I was thinking about to implement this would be to trick a molecular
replacement program into searching an anomalous Patterson map for the
requisite substructures, but I am not entirely sure about the best way to
implement this.

My questions are really two:

1. How much extra atom-finding power does one gain by telling the programs
the a priori structural information?

and

2. What would be the best way to implement this idea in the given software?

All the best,

Jacob Keller

***********************************
Jacob Keller
Northwestern University
6541 N. Francisco #3
Chicago IL 60645
(847)467-4049
j-keller2@northwestern.edu
***********************************

CCP4bb navigation

CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: Re: twwining operator
From: Phil Jeffrey pjeffrey {- at -} PRINCETON {- dot -} EDU
Date: 2007-05-21

Next message:
Subject: unstable performance of refmac. any suggestions?
From: fang sheng wuhanwuchang {- at -} HOTMAIL {- dot -} COM
Date: 2007-05-21