ISSN:
1600-5724
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
An example is given of phase extension for a small protein, avian pancreatic polypeptide, by the use of the Sayre-equation tangent formula (SETF). Initial data were the phase estimates of 129 reflexions with large values of |E| within the 3 Å resolution sphere. The mean error of these phases, estimated by a combination of isomorphous replacement and anomalous scattering, was 26.5°. Random values were then given to 1371 other phases out to 1 Å resolution and refinement was carried out with SETF. In 20 trials, 11 gave mean phase errors less than 34° for all 1500 reflexions with the best set having a mean phase error of 31-9°. Maps computed with these phases showed the general form of the molecule.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0108767388001552
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