ИСТИНА

In recent years, the increasing brightness of X-ray beamline for macromolecular crystallography has made it possible to obtained appropriative diffraction data for further procession by standard crystallographic software tools from crystals of very small size. To obtain bright enough diffraction spots we should deliver more radiation dose to the crystal, which leads to the critical radiation damage before we able to collect enough data to solve the crystal structure. However, if a few degrees of oscillation data per crystal are available, diffraction images can be processed by standard crystallographic software, and when the resulting partial datasets were checked for high level of isomorphism, them could be merged to produce the final complete data set. In present work the process of diffraction data collection from Escherichia coli bacteria Dps protein crystals 3-7 micron sized was described. The study of influence on final data set of various data collection parameters such as exposure time and diffraction wedge wideness per one crystal were carried out. Here, to achieve the best result in selecting the isomorphs partial datasets for merging hierarchical cluster analysis was applied. This method use distance between data sets a and b calculated from correlation coefficient (cc(a,b)) between common intensities of these sets ( ) as a metric for non-isomorphism. The calculations of these distance performed by ccCluster program [1]. Final diffraction data set consist of 256 monocrystal diffraction data, overall 450 monocrystals diffraction data was processed by XDS software [2]. The highest resolution of obtained structure is 2.2 Å, R-factor free value for this resolution equal 0.2598. Structure was deposited in PDB with unique four letter code as 6QVX.