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PDBsum entry 1uo6
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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On the routine use of soft X-Rays in macromolecular crystallography. Part ii. Data-Collection wavelength and scaling models.
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Authors
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C.Mueller-Dieckmann,
M.Polentarutti,
K.Djinovic carugo,
S.Panjikar,
P.A.Tucker,
M.S.Weiss.
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Ref.
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Acta Crystallogr D Biol Crystallogr, 2004,
60,
28-38.
[DOI no: ]
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PubMed id
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Abstract
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Complete and highly redundant data sets were collected at nine different
wavelengths between 0.80 and 2.65 A on a xenon derivative of porcine pancreatic
elastase in both air and helium atmospheres. The magnitude of the anomalous
signal, as assessed by the xenon-peak height in the anomalous difference
Patterson synthesis, is affected by the wavelength of data collection as well as
by the scaling model used. For data collected at wavelengths longer than 1.7 A,
the use of a three-dimensional scaling protocol is essential in order to obtain
the highest possible anomalous signal. Based on the scaling protocols currently
available, the optimal wavelength range for data collection appears to be
between 2.1 and 2.4 A. Beyond that, any further increase in signal will be
compensated for or even superseded by a concomitant increase in noise, which
cannot be fully corrected for. Data collection in a helium atmosphere yields
higher I/sigma(I) values, but not significantly better anomalous differences,
than data collection in air.
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Figure 1.
Figure 1 Schematic representation of the relevant absorption
coefficients in a diffraction experiment. The four different
coefficients are  [1]
for absorption in the crystal, [2]
for absorption in the mother liquor surrounding the crystal,
[3]
for absorption by the nylon loop used and [4]
for absorption in air (or helium).
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Figure 6.
Figure 6 I/  (I)
as a function of resolution (1/d^2) for the PPE-Xe data set
I-Air (black lines) and I-He (red lines). The dip at 3.5 Å
resolution in the upper curve is a result of the appearance of
an ice ring on the images of the later data sets.
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The above figures are
reprinted
by permission from the IUCr:
Acta Crystallogr D Biol Crystallogr
(2004,
60,
28-38)
copyright 2004.
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