Prof. Lisa Olshansky, University of Illinois Urbana Champaign
Seminar Title: Emergent Properties from Dynamicity: Exploring Conformational Control over Metal ion Reactivity
From the reduction of dinitrogen to the oxidation of water, the chemical transformations catalyzed by metalloenzymes underpin global geo- and biochemical cycles and represent some of the most kinetically and thermodynamically challenging processes known. The vast majority of these enzymes operate via a mechanism in which rate-limiting conformational changes precede chemistry. The commonality of this mechanistic pattern suggests that conformational gating may play an important role in mediating controlled and energy-efficient chemical transformations. To test this hypothesis, we have prepared and examined several synthetic and artificial systems in which conformational dynamicity correlates with metal ion reactivity. Creating conformationally dynamic coordination complexes, we’ve been able to modulate the kinetics of electron transfer reactivity in copper complexes, to access previously unobserved magnetic states in valence tautomeric cobalt complexes, and to control substrate binding events in dinuclear enzymatic models. Additionally, we’ve developed a new class of artificial metalloproteins in which allosteric binding events trigger protein conformational changes that in turn modulate the properties of an installed metallocofactor active site. Here, we report changes in ligation, reduction potential, and magnetic response as a function of allosterically-controlled protein conformation. All of these works aim to define and quantify the impacts of conformational dynamicity, and then to leverage those impacts in applications ranging from solar energy conversion, to biomedical imaging, and the development of novel (bio)catalyst systems.