Use of complementary cation and anion heavy-atom salt derivatives to solve the structure of cytochrome P450 46A1

Mark White, Natalia Mast, Ingemar Bjorkhem, Eric F. Johnson, C. David Stout, Irina A. Pikuleva

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

Human cytochrome P450 46A1 (CYP46A1) is one of the key enzymes in cholesterol homeostasis in the brain. The crystallization and heavy-atom structure solution of an active truncated CYP46A1 in complex with the high-affinity substrate analogue cholesterol-3-sulfate (CH-3S) is reported. The 2.6 Å structure of CYP46A1-CH-3S was solved using both anion and cation heavy-atom salts. In addition to the native anomalous signal from the haem iron, an NaI anion halide salt derivative and a complementary CsCl alkali-metal cation salt derivative were used. The general implications of the use of halide and alkali-metal quick soaks are discussed. The importance of using isoionic strength buffers, the titration of heavy-atom salts into different ionic species and the role of concentration are considered. It was observed that cation/anion-binding sites will occasionally overlap, which could negatively impact upon mixed RbBr soaks used for multiple anomalous scatterer MAD (MMAD). The use of complementary cation and anion heavy-atom salt derivatives is a convenient and powerful tool for MIR(AS) structure solution.

Original languageEnglish (US)
Pages (from-to)487-495
Number of pages9
JournalActa Crystallographica Section D: Biological Crystallography
Volume64
Issue number5
DOIs
StatePublished - Apr 19 2008

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Keywords

  • Alkali-metal salts
  • Cholesterol homeostasis
  • Cholesterol sulfate
  • Cytochrome P450 46A1
  • Halide salts
  • Heavy-atom derivatives
  • MAD
  • MIR
  • MIRAS

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Biophysics
  • Condensed Matter Physics
  • Structural Biology

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