Re: [ccp4bb] bigger size - > better diffraction?

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Subject: Re: bigger size - > better diffraction?
From: artem {- at -} XTALS {- dot -} ORG artem {- at -} XTALS {- dot -} ORG
Date: 2007-04-04

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Subject: Re: bigger size - > better diffraction?
From: Leonard Thomas thomasle {- at -} ITS {- dot -} CALTECH {- dot -} EDU
Date: 2007-04-04

Subject: Re: bigger size - > better diffraction?
From: Shane Atwell satwell {- at -} SGXPHARMA {- dot -} COM
Date: 2007-04-04

Streak seeding all your trays should give you a better handle on
nucleation. You might be too high in protein or precipitant w/o the
seeding, hence the showering and rare nice crystals.

Varying cryos, or cryo concentrations, or how the cryo is added can help
a lot. Try 5 or 6 different cryos at 3 concentrations each. When you
have the best nailed down then try sequential transfers of the crystals
from low to target concentrations (e.g. into 5% for a couple minutes,
then 10, 20, 25%). Also, you can try growing the crystals w/ a bit (5%)
or the final conc or cryo already present. Should help in getting them
habituated to the cryo.

Shane Atwell

> -----Original Message-----
> From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On
> Behalf Of Jenny
> Sent: Wednesday, April 04, 2007 5:50 AM
> To: CCP4BB@JISCMAIL.AC.UK
> Subject: [ccp4bb] bigger size - > better diffraction?
>
> Hi, All,
>
> I got a crystal that diffracts at 3.3A in house.The crystal
> size is about 0.2mm* 0.1mm * 0.2mm. At first I thought the
> size is fine,but it turns out the smaller ones diffract
> worse.I guess the reason is that
> the cell unit is really big (126.292 126.292 134.904 p4212,
> pretty big for a 10kD protein, isn't it?)
>
> So looks like I need to grow bigger crystals in order to get
> better diffractions.The problems is ,every time when I set up
> trays, the growing conditions is not exactly the same, so I
> have to set up a whole tray or maybe even 2 trays , then 2 or
> 3 conditions will jump out with good crystals ( 2 or 3
> nucleation site ) and some of the others will show lots lots
> of small crystals.I used NaCl as the salt, in a 4*6 tray, the
> [NaCl] is going from 2.0,2.05,2.1,2.15,....something like
> that and 0.05M does make big difference.I used Urea as the
> additive in this case ( 25 m ~ 100 mM) and tried
> 2+2,3+1,3+2, 3+1 ( 3 uL protein and 1 uL buffer ) is better
> than the other two cases.Right now it's growing in room temp
> in about a week.And crystals that not fresh got some bubbles
> around the edge and didn't diffract well.
>
> Does anyone have any suggestions that what I could do to
> improve the diffraction?
>
> Thanks a lot.
>
> Jenny
>

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Previous message:
Subject: Re: bigger size - > better diffraction?
From: artem {- at -} XTALS {- dot -} ORG artem {- at -} XTALS {- dot -} ORG
Date: 2007-04-04

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Subject: Re: bigger size - > better diffraction?
From: Leonard Thomas thomasle {- at -} ITS {- dot -} CALTECH {- dot -} EDU
Date: 2007-04-04