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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: "VAN RAAIJ , MARK JOHAN" mjvanraaij {- at -} CNB {- dot -} CSIC {- dot -} ES
Date: 2012-03-07
Next message:
Subject: Re: How to reduce no. of overlaps
From: Zhijie Li zhijie {- dot -} li {- at -} UTORONTO {- dot -} CA
Date: 2012-03-07


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

Yes... quite. Thanks!

(Beam, rotation axis... how can you expect me to keep all these
new-fangled inventions apart?!)



On 07/03/2012 07:33, VAN RAAIJ , MARK JOHAN wrote:
> 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,/*
>>>
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>>>
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>>>
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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: "VAN RAAIJ , MARK JOHAN" mjvanraaij {- at -} CNB {- dot -} CSIC {- dot -} ES
Date: 2012-03-07
Next message:
Subject: Re: How to reduce no. of overlaps
From: Zhijie Li zhijie {- dot -} li {- at -} UTORONTO {- dot -} CA
Date: 2012-03-07



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