Computational Insights into Five- versus Six-Coordinate Iron Center in Ferrous Soybean Lipoxygenase

Tao Yu, Alexander V. Soudackov, Sharon Hammes-Schiffer

Research output: Contribution to journalArticlepeer-review

Abstract

Soybean lipoxygenase (SLO) serves as a prototype for fundamental understanding of hydrogen tunneling in enzymes. Its reactivity depends on the active site structure around a mononuclear, nonheme iron center. The available crystal structures indicate five-coordinate iron, while magnetic circular dichroism experiments suggest significant populations of both five-coordinate (5C) and six-coordinate (6C) iron in ferrous SLO. Quantum mechanical calculations of gas phase models produce only 6C geometries. Herein mixed quantum mechanical/molecular mechanical (QM/MM) calculations are employed to identify and characterize the 5C and 6C geometries. These calculations highlight the importance of the protein environment, particularly two Gln residues in a hydrogen-bonding network with Asn694, the ligand that can dissociate. This hydrogen-bonding network is similar in both geometries, but twisting of a dihedral angle in Asn694 moves its oxygen away from the iron in the 5C geometry. These insights are important for future simulations of SLO.

Original languageEnglish (US)
Pages (from-to)3429-3433
Number of pages5
JournalJournal of Physical Chemistry Letters
Volume7
Issue number17
DOIs
StatePublished - Sep 1 2016

ASJC Scopus subject areas

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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