Redox and Electrocatalytic Properties of Mimochrome VI, a Synthetic Heme Peptide Adsorbed on Gold

Abstract

Mimochrome VI (MC-VI) is a synthetic heme peptide containing a helix-heme-helix sandwich motif designed to reproduce the catalytic activity of heme oxidases. The thermodynamics of Fe(III) to Fe(II) reduction and the kinetics of the electron-transfer process for MC-VI immobilized through hydrophobic interactions on a gold electrode coated with a nonpolar SAM of decane-1-thiol have been determined through cyclic voltammetry. Immobilization slightly affects the reduction potential of MC-VI, which under these conditions electrocatalytically turns over molecular oxygen. This work sets the premise for the exploitation of totally synthetic mimochrome-modified electrode surfaces for clinical and pharmaceutical biosensing.

Protein Design: Toward Functional Metalloenzymes

“…Mimochrome VI was then immobilized on a self-assembled monolayer (SAM)-coated gold electrode, and its electronic properties were studied with CV. 931 Mimochrome VI showed a quasi-reversible one-electron process. In particular, varying scan rates revealed that there are two conformers of mimochrome VI that possessed a high potential (−106 mV vs NHE) and a low potential (−131 mV vs NHE), respectively, which were hypothesized to correspond to the Δ and Λ conformations of the iron heme cofactor based on an analysis of the Cotton effects of the heme Soret band by CD spectroscopy.…”

Metal organic frameworks mimicking natural enzymes: a structural and functional analogy

“…Similar to the previous catalyst, 15.7 mL H 2 was observed after 1.5 h with a TON of 0.35 only. 273 Further exploitation of this artificial enzyme by simple peptide substitution afforded a modified analogue possessing impressive catalytic activity towards oxidation of 2,2 0 -azinobis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS). 26a).…”

“…Goff and co-workers recently followed a similar approach and immobilized a hemin unit onto the MWCNT surface coated with poly-pyrrole-imidazole (Fig. 273. 272 The imidazole unit coordinates to the distal position of the hemin unit leaving the sixth position vacant.…”

Enhancement of Peroxidase Activity in Artificial Mimochrome VI Catalysts through Rational Design

“…To tackle this challenge, we developed heme‐protein mimetics (mimochromes) by structure‐based design . Through a miniaturization process, we embedded the metalloporphyrin into a small peptide scaffold and systematically screened the effect of amino‐acid substitutions on function .…”