Rational Heme Protein Design: All Roads Lead to Rome

Abstract

Heme proteins are among the most abundant and important metalloproteins, exerting diverse biological functions including oxygen transport, small molecule sensing, selective CH bond activation, nitrite reduction, and electron transfer. Rational heme protein designs focus on the modification of the heme‐binding active site and the heme group, protein hybridization and domain swapping, and de novo design. These strategies not only provide us with unique advantages for illustrating the structure–property–reactivity–function (SPRF) relationship of heme proteins in nature but also endow us with the ability to create novel biocatalysts and biosensors.

An Artificial Heme Enzyme for Cyclopropanation Reactions

“…A common feature of these (designed) heme enzymes is that they contain a large hydrophobic substrate binding pocket orthogonal to the plane of the heme moiety. Alternatively, significant effort has been devoted to the de novo design of heme proteins, particularly based on 4‐helix bundles,21, 22, 23, 24, 25 antibodies, or other proteins,26, 27 yet none of these has found application in catalysis of new‐to‐nature reactions. A key difference is that these artificial heme enzymes generally do not present a defined binding site suitable for binding the often hydrophobic substrates.…”

The broad diversity of heme-protein cross-links: An overview

“…In natural heme proteins, the two propionate groups of heme usually form hydrogen-bonding interactions with the polypeptide chain and contribute to the heme stability [1][2][3][4][5][6][7][8][9][10][11]. Currently, there has been no discovery of a natural heme-protein cross-link involving the heme propionate group.…”

“…Mb has been favored as a scaffold protein for design of functional heme proteins [1,5,6,11,16,[80][81][82]. Recently, Lin, Tan and co-workers [83] engineered a tyrosine (F43Y mutation) in the heme distal pocket of sperm whale Mb, aiming to tune the binding of exogenous ligands using hydrogen-bonding interaction by the Tyr hydroxyl group.…”

“…1), to confer such diverse functions. This is attributed to the variety of interactions between the heme cofactor and the protein polypeptide chain, such as the coordination of heme iron by various axial ligands (His, Met, Cys, water, etc) and the hydrogen-bonding interactions in the heme distal pocket [1][2][3][4][5][6][7][8][9][10][11]. In addition to these interactions, post-translational modifications (PTMs) also play key roles in tuning the structure and function of heme proteins.…”

“…peroxidase and cytochrome P450, CYP450) to signaling (e.g. CO censor CooA) [1][2][3][4][5][6][7][8][9][10]. It is remarkable that heme proteins use the same heme cofactor, Fe-protoporphyrin IX (Fig.…”