Generation of New Artificial Metalloproteins by Cofactor Modification of Native Hemoproteins

Abstract

Heme can be removed from a number of native hemoproteins, thus forming corresponding apoproteins, each of which provides a site for binding of a metal complex. In one example, myoglobin, an O2 storage protein, can be reconstituted with iron porphycene to dramatically enhance the O2 affinity. Although it is known that myoglobin has poor enzymatic activity, the insertion of iron corrole or iron porphycene into apomyoglobin increases its H2O2‐dependent peroxidase/peroxygenase activities. Furthermore, reconstitution with manganese porphycene promotes hydroxylation of an inert CH bond. It is also of interest to insert a non‐porphyrinoid complex into an apoprotein. A cavity of apocytochrome c has been found to bind a diiron carbonyl complex, serving as a functional model of diiron hydrogenase. Aponitrobindin has a rigid β‐barrel structure that provides an excellent cavity for covalently anchoring a metal complex. A rhodium complex embedded in the cavity of genetically modified nitrobindin has been found to promote stereoselective polymerization of phenylacetylene.

Myoglobin-based non-precious metal carbon catalysts for an oxygen reduction reaction

“…Our group has been engaged in engineering of myoglobin (Mb), another representative hemoprotein ( Fig. 1) [38][39][40][41][42][43] which has not yet been explored as a possible NPMC precursor. Herein, we report the characterization of NPMCs prepared from Mb by heat treatment and an investigation of the ORR activity of these NPMCs under acidic conditions.…”

Advances in Engineered Hemoproteins that Promote Biocatalysis

“…Teale described a simple acidification and heme extraction technique which allowed for generations of hemoprotein researchers to easily exchange cofactors and explore new possibilities for functionalities as shown in Figure 2 [1]. Many decades later the utility of replacing the native heme cofactor with heme analogs has emerged as a strategy to produce synthetic metalloenzymes to function as robust biocatalysts [2][3][4][5][6][7][8][9][10].…”

“…Watanabe, Lu, and colleagues have spent a considerable effort in exploring the potential of these types of substitutions particularly in myoglobin where enantioselective sulfoxidation of thioanisole is shown with Watanabe's Cr III (Schiff-base)-myoglobin enhancing the oxidation rates by up to 15-fold comparatively to Cr III (Schiff-base) alone [8,10,22,[24][25][26]. These examples did show promising improved functionality in some cases, but others have proven to be difficult to isolate in high yields and/or require protein modification or some form of covalent anchor in order to handle efficiently.…”

Preface

“…In fact, this can be done by making mutations to existing proteins (Hu et al 2014; Nakajima, et al 2008), adding cofactors to systems that previously did not include such catalytic functionality (Dürrenberger et al 2014; Miner et al 2014), making protein fusions that provide photoaddressable proteins that localize in membranes (Hallett et al 2016), altering cofactors to serve a different purpose or attaching side chains (Hayashi et al 2015) or metal binding sites to confer new protein-protein interactions (PPIs) (Speltz et al 2015) or added stability (Salgado et al 2007; Schoene et al 2014). These PPIs are critical for molecular recognition, but often are difficult to measure in their native environments so that new methodologies have been developed to quantify these interactions in vivo (Cherf and Cochran 2015).…”

“…In terms of systems investigated, many design studies attempt to mimic or reproduce electron transfer (Zhang et al 2011,; Plegaria et al 2015b; Roy et al, 2014), structural (Lombardi et al 2000; Plegaria et al 2015a; Fragoso et al 2015; Mocny and Pecoraro 2015) or catalytic function (Cangelosi et al 2014; Durrenberger and Ward 2014; Miner et al 2014; Nakajima, et al 2008; Reig et al 2012; Tegoni et al 2012; Zastrow et al 2012). However, this field is not restricted to biomimics as new catalysis is explored by building unique cofactors (Dürrenberger and Ward 2014; Hayashi et al 2015; Popp and Ball 2010). Another area of great interest is the ability of a protein to recognize another protein or an inanimate surface.…”