Metal Complexation By Phytochelatins And Microcystins: A Molecular Dynamics Study

Abstract

A better understanding of the metal-peptide complexes formed by phytochelatins and microcystins is necessary to understand the role of these peptides in algal cells and cyanobacteria, respectively. As there are limited structural and thermodynamic data on these metal-peptide complexes, molecular simulations may provide useful insights by providing structural insights in concert with thermodynamic stability predictions. I conducted molecular dynamics simulations of complexes of phytochelatin (n=2), microcystin-LR, and microcystin-RR with Ca2+, Mg2+, Fe2+, Zn2+, and Cu2+. Structural characteristics of the resulting complexes agreed with results from other metal-peptide complexes. The simulation results also indicate that all three peptides bind Cu and Zn preferentially, supporting the peptides' roles in metal regulation. Peptide conformational changes after metal complexation shed light on the hypothesized transporters of the complexes from the cell, as well as on the environmental chemodynamics of the complexes and peptides in surface waters. iii