2013/09/18 by S.W.M. Tanley, Tanley, Simon W. M, Kay Diederichs +7
Biochemistry, Genetics and Molecular Biology · Materials Science · Medicine · Physics and Astronomy · #Biomolecules (q-bio.BM) #DNA and Nucleic Acid Chemistry #Drug Transport and Resistance Mechanisms #Enzyme Structure and Function #FOS: Biological sciences #Protein purification and stability #X-ray Spectroscopy and Fluorescence Analysis
paper · pdf · doi:10.48550/arxiv.1309.4661
openalex publication_date 2013/09/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Hen egg white lysozyme (HEWL) co-crystallisation conditions of carboplatin\nwithout sodium chloride (NaCl) have been utilised to eliminate partial\nconversion of carboplatin to cisplatin observed previously. Tetragonal HEWL\ncrystals were successfully obtained in 65% MPD with 0.1M citric acid buffer at\npH 4.0 including DMSO. The X-ray diffraction data resolution to be used for the\nmodel refinement was reviewed using several topical criteria together. The\nCC1/2 criterion implemented in XDS led to data being significant to 2.0 AA,\ncompared to the data only being able to be processed to 3.0 AA using the\nBruker software package (SAINT). Then using paired protein model refinements\nand DPI values based on the FreeR value, the resolution limit was fine tuned to\nbe 2.3 AA. Interestingly this was compared with results from the EVAL\nsoftware package which gave a resolution limit of 2.2 AA solely using\n<I/sigI> crossing 2, but 2.8 AA based on the Rmerge values (60%). The\nstructural results showed that carboplatin bound to only the N\δ binding\nsite of His-15 one week after crystal growth, whereas five weeks after crystal\ngrowth, two molecules of carboplatin are bound to the His-15 residue. In\nsummary several new results have emerged: - firstly non-NaCl conditions showed\na carboplatin molecule bound to His-15 of HEWL; secondly binding of one\nmolecule of carboplatin was seen after one week of crystal growth and two\nmolecules were bound after five weeks of crystal growth; and thirdly the use of\nseveral criteria to determine the diffraction resolution limit led to the\nsuccessful use of data to higher resolution.\n