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Re: [ccp4bb] How to reduce no. of overlaps

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CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999
Previous message:
Subject: Re: How to reduce no. of overlaps
From: Frank von Delft frank {- dot -} vondelft {- at -} SGC {- dot -} OX {- dot -} AC {- dot -} UK
Date: 2012-03-07
Next message:
Subject: Re: How to reduce no. of overlaps
From: Mark J van Raaij mjvanraaij {- at -} CNB {- dot -} CSIC {- dot -} ES
Date: 2012-03-07


Subject: Re: How to reduce no. of overlaps
From: Zhijie Li zhijie {- dot -} li {- at -} UTORONTO {- dot -} CA
Date: 2012-03-07

Hi,

Besides aligning the long axis with the rotation axis, which is the most important, there are a few more things that may help:

1) Try optimizing the freezing to reduce the mosaicity (if not ideal), or shoot at RT if possible. With higher mosaicity, the shape of the reflections are elongated in the reciprocal space, increasing the chance of overlapping.
2) Collect datesets in two runs, one with detector at far position to get more spacing between dots, another one at a closer position to get high res. Sometimes you may have to sacrifice some resolution for the completeness.
3) Shoot at a synchrotron with micro beam and a large detector.
4) Try integrating the images with both HKL2000 and mosflm. My past experience seems to suggest that mosflm is more tolerant to closely positioned reflections.

Zhijie


From: Dipankar Manna
Sent: Tuesday, March 06, 2012 11:56 PM
To: CCP4BB@JISCMAIL.AC.UK
Subject: [ccp4bb] How to reduce no. of overlaps


Dear Crystallographers,



I am working on a protein having SG P6, the cell parameters are a= 79, b= 79, c= 325. The crystals are forming in big size and with very good shape. It also diffracting very well in Home source facility both in terms of resolution and intensity. But the only problem is the number of overlaps. Its showing much more than the good spots. As a result the completeness is showing maximum up to 65% even after collecting 180 degrees. I am unable to get a complete data. I tried with reducing the oscillation angel to 0.3 degree/0.5 degree but it did not improve that much. Please give me some suggestions.



Regards,



Dipankar





Dipankar Manna

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CCP4bb navigation

CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999
Previous message:
Subject: Re: How to reduce no. of overlaps
From: Frank von Delft frank {- dot -} vondelft {- at -} SGC {- dot -} OX {- dot -} AC {- dot -} UK
Date: 2012-03-07
Next message:
Subject: Re: How to reduce no. of overlaps
From: Mark J van Raaij mjvanraaij {- at -} CNB {- dot -} CSIC {- dot -} ES
Date: 2012-03-07



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