Issue 17, 2015

An artificial heme-enzyme with enhanced catalytic activity: evolution, functional screening and structural characterization

Abstract

Synthetic proteins represent useful tools for reproducing metalloprotein functions in minimal, well-defined scaffolds. Herein, we describe the rational refinement of function into heme-protein models from the Mimochrome family. Originally designed to mimic the bis-His cytochrome b, the Mimochrome structure was modified to introduce a peroxidase-like activity, by creating a distal cavity on the heme. The success with the first asymmetric system, Mimochrome VI (MC6), gave the opportunity to explore further modifications in order to improve the catalytic activity. Starting from ferric MC6, single amino acid substitutions were introduced in the peptide chains to obtain four compounds, which were screened for peroxidase activity. The detailed structural and functional analysis of the best analogue, FeIII-E2L(TD)-MC6, indicates that an arginine residue in proximity to the heme-distal site could assist with catalysis by favoring the formation of the intermediate “compound I”, thus mimicking R38 in HRP. This result highlights the potential of using small scaffolds for exploring the main factors that tune the heme-protein activity, and for programming new desired functions.

Graphical abstract: An artificial heme-enzyme with enhanced catalytic activity: evolution, functional screening and structural characterization

Supplementary files

Article information

Article type
Paper
Submitted
14 Nov 2014
Accepted
10 Feb 2015
First published
10 Feb 2015

Org. Biomol. Chem., 2015,13, 4859-4868

Author version available

An artificial heme-enzyme with enhanced catalytic activity: evolution, functional screening and structural characterization

R. Vitale, L. Lista, C. Cerrone, G. Caserta, M. Chino, O. Maglio, F. Nastri, V. Pavone and A. Lombardi, Org. Biomol. Chem., 2015, 13, 4859 DOI: 10.1039/C5OB00257E

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