Functional artificial heme proteins Michael L. Klein, University of Pennsylvania, DMR 0520020

1. Functional artificial heme proteinsMichael L. Klein, University of Pennsylvania, DMR 0520020 Maquettes, simplified versions of natural proteins are used to decipher membrane-protein function-structure relationships & to reproduce functional elements of biological energy transduction. Design principles for scaffold assembly & cofactor binding have been established and maquettes reproduce function, including O2 and CO binding. Maquette HP7 with a “waterproof” interior favors O2 over CO binding far more than any natural distal histidine site, including oxygen transport proteins myoglobin and hemoglobin. The exclusion of water from the binding site predicts that amphiphilic maquettes, designed to span membranes, should retain oxygen binding capability. We have analyzed O2 and CO binding to maquettes with three heme binding sites. While all three sites bind CO, only the heme binding site in the hydrophilic domain binds O2. Stopped-flow spectral changes of the reduced heme B protein maquettes AP6a (Left) and HP7 (Middle)mixed with oxygen shows the transformation of the reduced heme (blue) to the oxy-ferrous state (red), which eventually becomes oxidized (green) as illustrated in the scheme (Right). Support: NSF MRSEC 0520020