Thank you for your email.
the anisotropic resolutions of the datasets are 5.6-7.1A for the best
and worst diffracting directions of the crystal without additive, and
4.0-5.8A for the crystal with additive.
The two crystals come from the same prep and same drop setup, only
differ from the presence of the additive during crystallogenesis. They
are indeed two different crystals, I would be curious to know more how
to compare these two datasets together as I thought it was not possible
with such different cell parameters.
On 31/05/2017 17:12, Eleanor Dodson wrote:
Well - you dont give details o f resolution but the sovent content and
the peak of 0.51 would suggest a possible dimer in crystal 1
Crystal 2 is so different it might well have a dimer in a different
orientation.
Yes, it could very well be the case. But wouldn't there be a peak as
well in the SRF?
I would try to see if there was a relationship between Xtal 1 and Xtal
2 - can tell you how I would do that if you are interested..
But doesnt mass spec or some such technique suggest whether there is a
dimer or not?
I am not aware of a way to test by Mass Spec or other techniques the
content of the ASU, I would be very interested if anyone can further my
knowledge on this.
All the best
Vincent
Eleanor
Self Rotation Functions are a) hard to interpret and b) often misleading!
On 31 May 2017 at 14:18, vincent Chaptal <vincent.chap...@ibcp.fr
<mailto:vincent.chap...@ibcp.fr>> wrote:
Dear all,
I need help interpreting results from a SRF; I am very naïve at
interpreting them and would appreciate any pointer...
I have 2 crystals, before and after additive during
crystallogenesis. They have different cell parameters, and I am
wondering if I have a monomer or a dimer in the ASU, and if the
additive changed this.
*crystal w/o additive:*
P21 114,5 107,6 134,6 beta=95,74
1monomer in the ASU = 80% solvent, 1 dimer in the ASU = 61%
solvent. Note that this high solvent content agrees well with the
fact that this is a membrane protein, and diffracts both to low
resolution and very anisotropic...
SRF from Molrep:
+------------------------------------------+
| theta phi chi P(i)/P(0)|
+------------------------------------------+
| 1 0.00 0.00 0.00 1.00 |
| 2 148.48 0.00 180.00 0.51 |
| 3 161.29 0.00 180.00 0.31 |
| 4 105.34 180.00 180.00 0.30 |
| 5 74.78 -56.26 179.58 0.27 |
| 6 15.14 -163.78 180.00 0.25 |
| 7 67.61 -40.16 180.00 0.24 |
| 8 134.54 -180.00 180.00 0.19 |
| 9 72.33 -37.82 180.00 0.18 |
| 10 69.72 38.92 175.62 0.18 |
| 11 110.28 -141.08 175.62 0.18 |
| 12 96.58 101.90 179.79 0.18 |
| 13 67.04 -15.02 179.71 0.18 |
| 14 62.76 -15.52 179.45 0.17 |
| 15 117.26 164.48 179.45 0.17 |
| 16 68.39 -18.92 179.86 0.17 |
| 17 70.52 -16.51 180.00 0.17 |
| 18 24.05 -162.02 179.98 0.17 |
| 19 78.61 -36.36 180.00 0.17 |
| 20 83.17 78.42 173.34 0.16 |
| 21 96.83 -101.58 173.34 0.16 |
| 22 81.25 -75.03 179.73 0.16 |
| 23 81.81 -17.73 180.00 0.16 |
| 24 11.02 -142.22 180.00 0.16 |
| 25 76.14 -16.64 179.71 0.16 |
| 26 76.56 -16.93 180.00 0.16 |
| 27 162.29 32.44 180.00 0.16 |
| 28 10.03 -136.82 180.00 0.15 |
| 29 68.67 -58.10 179.49 0.15 |
| 30 111.33 121.90 179.49 0.15 |
| 31 62.99 -20.19 180.00 0.14 |
| 32 97.24 145.00 179.78 0.14 |
| 33 99.56 165.86 179.74 0.14 |
| 34 84.27 -82.68 180.00 0.14 |
| 35 84.51 72.76 174.42 0.13 |
+------------------------------------------+
Crystal with additive:
P21
CELL 117.2840 110.3330 155.6880 90.0000 93.4280 90.0000
1 monomer in the ASU = 84% solvent, 1 dimer = 68% solvent.
SRF from Molrep:
+------------------------------------------+
| theta phi chi P(i)/P(0)|
+------------------------------------------+
| 1 0.00 0.00 0.00 1.00 |
| 2 59.55 0.00 180.00 0.36 |
| 3 156.11 0.00 180.00 0.29 |
| 4 10.00 -165.58 180.00 0.26 |
| 5 110.22 -180.00 180.00 0.26 |
| 6 12.97 -169.15 180.00 0.23 |
| 7 166.21 -9.06 180.00 0.22 |
| 8 81.64 -9.61 179.74 0.21 |
| 9 86.02 80.72 178.22 0.20 |
| 10 93.98 -99.28 178.22 0.20 |
| 11 5.96 -54.00 180.00 0.19 |
| 12 67.40 -10.81 180.00 0.19 |
| 13 87.10 -94.56 179.91 0.19 |
| 14 147.13 47.70 10.71 0.19 |
| 15 147.13 -47.70 10.71 0.19 |
| 16 87.45 91.04 155.74 0.19 |
| 17 92.55 -88.96 155.74 0.19 |
| 18 5.33 -63.00 180.00 0.19 |
| 19 104.60 169.61 179.59 0.19 |
| 20 88.01 -85.32 179.05 0.18 |
| 21 92.02 94.64 179.68 0.18 |
| 22 87.61 91.31 153.16 0.18 |
| 23 92.39 -88.69 153.16 0.18 |
| 24 6.65 -46.80 180.00 0.18 |
| 25 153.26 36.01 21.16 0.18 |
| 26 153.26 -36.01 21.16 0.18 |
| 27 63.11 -11.30 179.51 0.18 |
| 28 76.82 -5.09 179.61 0.18 |
| 29 87.69 91.37 148.72 0.18 |
| 30 92.31 -88.63 148.72 0.18 |
| 31 86.74 -9.44 179.90 0.17 |
| 32 85.83 80.82 148.49 0.17 |
| 33 94.17 -99.18 148.49 0.17 |
| 34 175.25 57.61 180.00 0.17 |
| 35 4.63 -90.00 180.00 0.17 |
+------------------------------------------+
Can I say that the peak at 0.51 in the crystal without additive is
significant, concluding that there is probably a dimer in the ASU
in that crystal, in contrast to the crystal with additive where no
peak stands out, which would lean towards a monomer in the ASU?
Thank you for your help.
Best
Vincent
--
Vincent Chaptal, PhD
Institut de Biologie et Chimie des Protéines
Drug Resistance and Membrane Proteins Laboratory
7 passage du Vercors
69007 LYON
FRANCE
+33 4 37 65 29 01 <tel:+33%204%2037%2065%2029%2001>
http://www.ibcp.fr
--
Vincent Chaptal, PhD
Institut de Biologie et Chimie des Protéines
Drug Resistance and Membrane Proteins Laboratory
7 passage du Vercors
69007 LYON
FRANCE
+33 4 37 65 29 01
http://www.ibcp.fr
