A Biosynthetic Approach Toward Biomimetic Studies of Metalloproteins Involved in Long-range Electron Transfer

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

This award in the Inorganic, Bioinorganic and Organometallic Chemistry program supports research by Professor Yi Lu and the University of Illinois at Urbana-Champaign to gain a deeper understanding of the coordination chemistry and biological role of electron transfer (ET) at metal ion centers such as CuA and [Fe2S2] in proteins by applying two new techniques from biology, i.e. expressed protein ligation (EPL) and loop-directed mutagenesis (LDM). Unnatural amino acids will be introduced by EPL in order to make isostructural substitutions that will make it possible to elucidate the roles of the residues in the primary and secondary coordination sphere of the CuA center in azurin more precisely in determining a) geometric structures, such as the Cu-Cu bond distance and the "diamond core" angle; b) electronic structure, such as the extent of electron delocalization and c) functional properties, such as the reduction potentials and electron transfer rates of the center. LDM will be used to place three prominent ET centers (blue copper, CuA and [Fe2S2] centers) in the same protein framework of azurin, allowing a direct comparison of their structural and functional properties, such as extent of electron delocalization and ET efficiency. Insights obtained from the study will allow the design of metal-binding sites with tunable redox and electron-transfer properties, which is important to biological respiration (in the case of cytochrome oxidase) and the global nitrogen cycle (in the case of N2O-reductase). Introducing two new techniques from biology also allows the advancement of basic coordination chemistry. Lecture and lab modules (including quizzes) will be developed to integrate multidisciplinary research into graduate and undergraduate course instruction. A course called "Chemistry and Biology of Everyday Life" will be enhanced using materials from this research. To broaden participation of underrepresented groups, the PI will give seminars at institutions and summer camps, and participate in summer research opportunity programs.