An online webserver and database for the identification of contaminant crystals

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Our choice of using the full MR search power on pre-selected contaminants, as opposed to using a full brute-force search optimised for speed, results in certain advantages and disadvantages. The disadvantages are that (i) only contaminants are detected that are known and present in the ContaBase; and that (ii) the speed of detection ranges from 5 minutes to up to several hours in difficult cases. The advantages are that (i) by providing a carefully curated MR database we minimise the rate of false positives and hence the time spent for manual inspections of all MR solutions produced from non-contaminant structural homologues (especially when data are anisotropic, twinned or of low-resolution); (ii) the precise MR search with several search models allows detection of contaminants in difficult cases (e.g. high copy number in the ASU, twinning, anisotropy, low resolution, protein conformational changes or partial proteolytic cleavage) with a higher success rate than speed-optimised brute force approaches, or with a higher speed than full MR brute-force approaches. ContaMiner and high-speed brute-force algorithms, once they become available, will therefore be highly complementary approaches.

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