A Ferrocene–Peptide Conjugate as a Hydrogenase Model System

Abstract

This work introduces a bis(cysteine) ligand to build a small peptidic model system of hydrogenase enzymes. Fe(C5H4CO–Cys–OMe)2 (LH2) has been employed as a chelate for an iron–carbonyl complex, which mimics two essential structural properties of the hydrogenase class of enzymes, namely the coordination of the iron–carbonyl core to peptide ligands and the presence of an electrochemical relay in spatial proximity. The treatment of LH2 with Fe3(CO)12 yields LFe2(CO)6 (3a), which is the first peptide‐coordinated iron hydrogenase active‐site model complex. Compound 3a was fully characterized spectroscopically (1H NMR, 13C NMR, IR and Mössbauer spectroscopy, mass spectrometry and elemental analysis). A single‐crystal X‐ray analysis confirms the proposed structure and reveals a staggered conformation of the Fe2(CO)6S2 core. Fourier transform infrared (FTIR) spectroelectrochemistry reveals an electronic interaction between the peptide backbone and the iron–carbonyl cluster, but not with the ferrocene subsite. The introduction of this peptidic cysteine‐based ligand into hydrogenase model chemistry helps to confirm the proposed cofactor biosynthesis and understand the electronic interplay between the metal–carbonyl active site and the protein environment in this important class of enzymes.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Investigation of amino acid containing [FeFe] hydrogenase models concerning pendant base effects

“…So far only little attention has been devoted towards mimicking the enzymatic environment of the H-cluster. To our best knowledge, only two examples are known in literature containing the naturally occurring amino acid cysteine as ligand for [FeFe] hydrogenase model complexes [21,22].…”

Spectroscopic and Electrochemical Investigations into the Interactions of Metal Ions with a Ferrocenoyl–Histidine Peptide Conjugate

“…Metzler-Nolte and coworkers recently reported the structure of an Fc-cysteine derivative in which the two Cys sulfur atoms coordinate to an Fe-carbonyl fragment. [5] Hirao et al reported a Pd 2+ complex of an Fc-peptide-pyridine conjugate in which a Pd 2+ ion is coordinated to the two pyridine ligands. [6] Results on a cyclic Fc-His derivative show that alkali metals can coordinate presumably to the amide carbonyl groups, giving rise to significant changes in the redox potential of the Fc core.…”

A Novel Organometallic ReI Complex with Favourable Properties for Bioimaging and Applicability in Solid‐Phase Peptide Synthesis

“…[1] A useful strategy to enhance the bioavailability and target specificity of potentially active compounds is to link them to biological vectors such as peptides, carbohydrates or hormones. [2] In the past we have reported on the successful synthesis of peptide bioconjugates for such purposes, in which we have used a range of different transition metal complexes based on iron, [3][4][5] copper, [6] zinc, [6] cobalt, [4,[7][8][9] ruthenium, [10,11] rhenium, [12] platinum [12] and molybdenum. [13] One major advantage of peptide-based conjugates is their variability.…”