Synthetic analogues of [Fe 4S 4(Cys) 3(His)] in hydrogenases and [Fe 4S 4(Cys) 4] in HiPIP derived from all-ferric [Fe 4S 4{N(SiMe 3) 2} 4]

Yasuhiro Ohki, Kazuki Tanifuji, Norihiro Yamada, Motosuke Imada, Tomoyuki Tajima, Kazuyuki Tatsumi

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22 Citations (Scopus)

Abstract

The all-ferric [Fe 4S 4] 4+ cluster [Fe 4S 4{N(SiMe 3) 2} 4] 1 and its one electron reduced form [1] - serve as convenient precursors for the synthesis of 3:1-site differentiated [Fe 4S 4] clusters and highpotential iron-sulfur protein (HiPIP) model clusters. The reaction of 1 with four equivalents (equiv) of the bulky thiol HSDmp (Dmp= 2,6-(mesityl) 2C 6H 3, mesityl =2,4,6-Me 3C 6H 2) followed by treatment with tetrahydrofuran (THF) resulted in the isolation of [Fe 4S 4(SDmp) 3(THF) 3] 2. Cluster 2 contains an octahedral iron atom with three THF ligands, and its Fe(S) 3(O) 3 coordination environment is relevant to that in the active site of substrate-bound aconitase. An analogous reaction of [1] - with four equiv of HSDmp gave [Fe 4S 4(SDmp) 4] - 3, which models the oxidized form of HiPIP. The THF ligands in 2 can be replaced by tetramethyl-imidazole (Me 4Im) to give [Fe 4S 4(SDmp) 3(Me 4Im)] 4 modeling the [Fe 4S 4(Cys) 3(His)] cluster in hydrogenases, and its one-electron reduced form [4] - was synthesized from the reaction of 3 with Me 4Im. The reversible redox couple between 3 and [3] - was observed at E 1/2=-820 mV vs. Ag/Ag +, and the corresponding reversible couple for 4 and [4] - is positively shifted by +440 mV. The cyclic voltammogram of 3 also exhibited a reversible oxidation couple, which indicates generation of the all-ferric [Fe 4S 4] 4+ cluster, [Fe 4S 4(SDmp) 4].

Original languageEnglish
Pages (from-to)12635-12640
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume108
Issue number31
DOIs
Publication statusPublished - Aug 2 2011
Externally publishedYes

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Keywords

  • Fe4S4 cluster
  • Thiolates

ASJC Scopus subject areas

  • General

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