[Seminar] 57Fe nuclear resonance vibrational spectroscopy of metalloenzymes

Title: ⁵⁷Fe nuclear resonance vibrational spectroscopy of metalloenzymes

Speaker: Lars Lauterbach

Affiliation: Technical University of Berlin

Abstract: Nuclear resonance vibrational spectroscopy (NRVS) is a synchrotron radiation-based technique that selectively probes iron-specific normal modes and the related molecular coordinates. 

We applied ⁵⁷Fe NRVS to probe ferredoxins containing single Fe-S cluster and a multi-cofactor- containing hydrogenase to obtain insights into the redox-dependent dynamics of the iron-containing cofactors. The NRVS spectra obtained with ferredoxins, which contain either a [3Fe–4S] or a [4Fe–4S] cluster, revealed vibrational property changes related to the electronic and structural propterties of the both Fe–S clusters.

This corresponding study served as the basis for the analysis of the more sophisticated NAD⁺-reducing hydrogenase (SH) from Ralstonia eutropha. The SH contains an H₂-cycling catalytic [NiFe] center, two flavin mononucleotides, an electron relay consisting of four [4Fe4S] clusters and one [2Fe2S] species and the NAD(H)-binding site. In order to obtain insights into the structure of the [NiFe] site and the [FeS] clusters, we have performed NRVS on both oxidized and reduced SH. Our data indicate that only two of five [FeS] clusters became reduced upon treatment of the SH with NADH. Externally added gaseous ¹³CO was incorporated into the [NiFe] center of the SH and allowed the discrimination of the vibrational bands related to the CN and CO ligands of the iron in the [NiFe] active site.

In my lecture, I will give a basic overview on NRVS and the general experimental setup required to perform NRVS measurements. Finally, application of NRVS on further metalloenzymes will be discussed.