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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: Frank von Delft frank {- dot -} vondelft {- at -} SGC {- dot -} OX {- dot -} AC {- dot -} UK
Date: 2012-03-07


Subject: Re: How to reduce no. of overlaps
From: "VAN RAAIJ , MARK JOHAN" mjvanraaij {- at -} CNB {- dot -} CSIC {- dot -} ES
Date: 2012-03-07

typo correction, you'll want the long axis parallel to the rotation
axis, not to the beam.
Mark

Quoting Frank von Delft:

> You probably have to tilt your crystal, so that the long axis is
> parallel to the beam. We do this routinely: cut a plastic pipette
> tip to have a sharp point, then push the loop where it attaches to
> the pin, to bend the crystal itself.
>
> You have to identify from your diffraction whether the long axis is
> pointing through the face or the edge of the loop. As it's P6,
> chances are it's through the face, because long-axis P6 tends to
> make flat hexagons which lie flush with the face. So you have to
> bend so the face of the loop upwards.
>
> You'll have to practice this first, though, so put up an empty loop.
> Top tips:
> * Don't breathe! You'll blow the cryostream away.
> * Bend the loop towards (rather than away from) the rim edge of
> the pin to which it's glued.
> * Don't breathe!
> * Practise practise practise.
>
>
> Another thing: most in-house sources allow you to reduce divergence
> of the beam. You lose intensity, but no matter, just expose longer.
> That also improves overlap.
>
> Cheers
> phx
>
>
>
> On 07/03/2012 04:56, Dipankar Manna wrote:
>>
>> 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/
>>
>> */Aurigene Discovery Technologies Limited,/*
>>
>> /#39-40 KIADB Industrial Area, Electronic City, Phase II,/
>>
>> /Hosur Road, Bangalore- 560 100, India/
>>
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Office Ph : +91 80-66204422 (Extn: 398)
>>
Email ID: dipankar_m@aurigene.com/
>>
>>
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>



Mark J van Raaij
Laboratorio M-4
Dpto de Estructura de Macromoléculas
Centro Nacional de Biotecnología - CSIC
c/Darwin 3, Campus Cantoblanco
28049 Madrid
tel. 91 585 4616
email: mjvanraaij@cnb.csic.es

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: Frank von Delft frank {- dot -} vondelft {- at -} SGC {- dot -} OX {- dot -} AC {- dot -} UK
Date: 2012-03-07



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