Consideration of Lewis Acidity in the Context of Heme Biochemistry: A Molecular Visualization Exercise

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 3 Issue 3(1998), S1430-4171(98)03206-7

Consideration of Lewis Acidity in the Context of Heme Biochemistry: A Molecular Visualization Exercise

Timothy E. Elgren

Department of Chemistry, Hamilton College, Clinton, New York 13323

Published online: 1 June 1998

Abstract. Molecular visualization software is widely available and readily incorporated into a variety of teaching environments. By taking full advantage of the wealth of structural information available, relationships between structure and reactivity are readily extracted. These exercises are designed to engage students in discussions that invoke principles introduced in general chemistry (e.g., Lewis acidity, hydrogen bonding, reduction potentials) and are presented here in the context of heme biochemistry. Students are asked to determine the coordination environment of the iron center for several heme proteins and use these structures to predict relative reactivities toward dioxygen and/or hydrogen peroxide. What they discover is that perturbation of the axial ligand(s) has a profound effect on the Lewis acidities of these metal centers and thus on heme iron reactivity. Therefore, their diverse reactivities can be rationalized as a natural consequence of their bioinorganic coordination chemistry. Several questions are posed to initiate further discussion.

Key Words: Computers in Chemistry; general chemistry; visualization; biochemistry

(*) Corresponding author. (E-mail: TElgren@hamilton.edu)

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