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
http://www.ibcp.fr
