[ccp4bb] SUMMARY: Main topic of the day: Protein crystallization

Protein crystallography Programs for crystallography X-ray detectors
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Date: 2007-03-05

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Subject: SUMMARY: Main topic of the day: Protein crystallization
From: Ronaldo Alves Pinto Nagem nagem {- at -} ICB {- dot -} UFMG {- dot -} BR
Date: 2007-03-05

Dear CCP4bb users,

I would like to thank everyone who answered my question and apologize for
my delay in posting the summary. Here is the question and the answers I
got.

What was the minimun protein concentration reported with success in
crystallization trials?

We've done crystallization at 1.2 mg/ml (which was pushing it for that
protein), and in some cases, depending on protein solubility of course, we
are required to use less than that. We have a protein that (at the
moment) precipitates at under 1mg/ml.
Gerald Audette

I have one with 1.8 mg/ml but this was not due to solubility issues but
more not enough protein and desperation mode to set up trays :-)
Jürgen Bosch

We have at least 1 example where the protein (a large kinase) crystallizes
at 2-3 mg/ml but you need seeding
Alexander Pautsch

I have a database of crystallization conditions extracted from the PDB. I
was able to parse the data to extract the concentration of protein in
around 900 cases.
The lowest 9 protein concentrations were as follows:

PDB ID TYPE DATE Protein
conc, mg/ml
1EYM ISOMERASE. 07/05/2000 0.75
1ADQ COMPLEX (IMMUNOGLOBULIN/AUTOANTIGEN) 18/02/1997 1
1W5G FOUR HELIX BUNDLE. 06/08/2004 1
1UU4 HYDROLASE. 15/12/2003 1
1W2U HYDROLASE. 08/07/2004 1
1DXP SERINE PROTEASE. 13/01/2000 1
1DY8 SERINE PROTEASE. 18/01/2000 1
1DY9 SERINE PROTEASE. 31/01/2000 1
1DG6 APOPTOSIS. 23/11/1999 1.2

The maximum protein conc was 200 mg/ml (1BLF)
My database goes up to October 2004. Janet Newman and Tom Peat have done
this job far more conscientiously and could probably give you better and
more up-to-date data.
Patrick Shaw Stewart

Just to add that in one case we were able to get suitable crystals after
using a protein concentration of as low as 1.5 mg/ml (kapetaniou et al.
Acta Cryst. 2005, F61, 479-481) and microdialysis to slowly remove the
excess of salt. Lower concentrations (0.50-0.75 mg/ml) could also produce
crystals but they were too small.
Tassos Papageorgiou

We have one protein (bacterial antitoxin HigA, 2ICT) that crystallizes in
many conditions (30-40) at 0.3-0.6 mg/ml; the crystals diffract to 1.63 A.
Mark Arbing

Once again, thank you for your answers.

Ronaldo.

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CCP4bb <-- 2007 <-- March 2007 <-- 05 March 2007

Previous message:
Subject: Re: luzzati numbers in ccp4/refmac
From: Edwin Pozharski epozh001 {- at -} UMARYLAND {- dot -} EDU
Date: 2007-03-05

Next message:
Subject: Problems in MR
From: thunderbird thunderbird {- at -} MOON {- dot -} IBP {- dot -} AC {- dot -} CN
Date: 2007-03-05