Page 85 - Macromolecular Crystallography

74 MACROMOLECULAR CRYS TALLOGRAPHY

4. Load in a frame 1 of the data and check the Garman, E. (2003). ‘Cool’ crystals: macromolecular cry-
resolution to which the diffraction extends. Look ocrystallography and radiation damage. Curr. Opin.
for pathologies in the diffraction pattern, such as Struct. Biol. 13, 545–551.
split spots or ill-defined, blurred reflections. Check Garman, E. F. and Schneider, T. R. (1997). Macromolecular
also the frames at 45 ◦ away and 90 ◦ away for crystallography. J. Appl. Cryst. 30, 211–237.
Hicks, L. M., Hunt J. L. and Baxter C. R. (1979). Liquid
similar pathologies. If such pathologies are present,
propane cold injury: a clinicopathologic and experi-
it is worth mounting another crystal as it could
mental study. J. Trauma 19, 701–703.
be that not all crystals suffer the same problems.
Hope, H. (1988). Cryocrystallography of biological macro-
Otherwise it could be that the crystals are inher- molecules: a generally applicable method. Acta Crystal-
ently mosaic (the solution is to check a frame logr. B 44, 22–26.
collected on a capillary-mounted crystal as inap- Jin, X., Touhey, J. and Gaudet, R. (2006). Structure of the
propriate cryoprotectant can increase mosaicity), N-terminal ankyrin repeat domain of the TRPV2 ion
or they could be twinned (the solution is depen- channel. J. Biol. Chem. 281, 25006–25010.
dent on the nature of the twinning, if the data is Kabsch, W. (1988a). Evaluation of single crystal X-ray
indexable this may be sorted out after the event diffraction data from a position-sensitive detector. J. App.
Cryst. 21, 63–70.
using detwinning software, otherwise effort may
Kabsch, W. (1988b). Automatic indexing of rotation diff-
have to be spent growing untwinned crystals by
raction patterns. J. App. Cryst. 21, 67–71.
changing the conditions or adding additives such as
Kabsch, W. (1993a). Data collection and processing. In:
dioxane).
Sawyer, L., Issacs, N. and Bailey, S., eds. Proceed-
5. Start indexing the frames with your favourite ings of the CCP4 Study weekend. Daresbury laboratories,
software package, HKL2000, MOSFLM, etc. Two Warrington, UK, pp. 56–62.
examples are given in Figs 4.9 to 4.12, one for an Kabsch, W. (1993b). Automatic processing of rotation
indexing with MOSFLM (Fig. 4.9 without predic- diffraction data from crystals of initially unknown sym-
tions and Fig. 4.10 showing the predictions) and metry and cell constants. J. App. Cryst. 26, 795–800.
the other for HKL2000 (Fig. 4.11 without the pre- Kriminski, S., Kazmierczak, M. and Thorne, R. E. (2003).
dictions and Fig. 4.12 with the predictions). The Heat transfer from protein crystals: implications for
crystal in question is of a rat TRPV2 Ankyrin flash-cooling and X-ray beam heating. Acta Crystallogr.
D 59, 697–708.
Repeat Domain protein (Jin et al., 2006). The
Kwong, P. D. and Liu, Y. (1999). Use of cryoprotectants
space group is P2 1 2 1 2 1 and the cell parameters are
in combination with immiscible oils for flash cooling
a = 41.0 Å, b = 57.5 Å, c = 139.5 Å, α = β = γ =
macromolecular crystals. J. Appl. Cryst. 32, 102–105.
◦
90 . Once a decision has been made on the space- Leslie, A. (1993). Data collection and processing. In: Pro-
group it always pays to integrate in the background ceedings of the CCP4 Study Weekend, Sawyer, L., Isaacs, N.
as the data collection is proceeding. This can be and Bailey, S. eds. Daresbury Laboratories, Warington,
very instructive as integration statistics can indicate UK, pp. 44–51.
whether problems of initial space-group definition Lusty, C. J. (1999). A gentle vapor-diffusion technique for
have arisen. For example one does not wish to leave cross-linking of protein crystals for cryocrystallography.
a synchrotron and return home to find that the true J. Appl. Cryst. 32, 106–112.
Mitchell, E. P. and Garman, E. F. (1994). Flash-freezing
space-group was of a lower symmetry and insuf-
of protein crystals: investigation of mosaic spread and
ficient data has been collected or that the data is
diffraction limit with variation of cryprotectant concen-
giving terrible merging statistics as indicated by a
tration. J. Applied Crystallogr. 27, 1070–1074.
worsening R-merge during data collection.
Otwinowski, Z. and Minor, W. (1997). Processing of X-ray
diffraction data collected in oscillation mode. Method
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