[ccp4bb] bigger size - > better diffraction?

- Protein crystallography

Main steps:

- Protein purification
- Crystallisation

Special:

- Programs for crystallography
- X-ray detectors

Basic tutorials:

   - Chemistry
   - Protein
   - Peptide
   - Amino Acids

Xtal community:

- CCP4BB

CCP4bb navigation

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

Previous message:
Subject: EBSA/BBS Eurobiophysics Congress, London, July 2007
From: Elspeth Garman elspeth {- at -} BIOP {- dot -} OX {- dot -} AC {- dot -} UK
Date: 2007-04-04

Next message:
Subject: Re: bigger size - > better diffraction?
From: Jenny ruisher {- at -} GMAIL {- dot -} COM
Date: 2007-04-04

Subject: bigger size - > better diffraction?
From: Jenny ruisher {- at -} GMAIL {- dot -} COM
Date: 2007-04-04

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

CCP4bb navigation

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

Previous message:
Subject: EBSA/BBS Eurobiophysics Congress, London, July 2007
From: Elspeth Garman elspeth {- at -} BIOP {- dot -} OX {- dot -} AC {- dot -} UK
Date: 2007-04-04

Next message:
Subject: Re: bigger size - > better diffraction?
From: Jenny ruisher {- at -} GMAIL {- dot -} COM
Date: 2007-04-04