Thesis Defense: Shah Alam Limon, Physics, Astronomy & Materials Science

STUDY OF IRON ION TRANSIT THROUGH

THREE-FOLD CHANNEL OF FERRITIN CAGE

Ferritin is an iron-storage protein with an ability to uptake, mineralize and release iron ions in a controllable manner. Understanding of the detailed molecular functioning of ferritin is required for rational design of biomimetic conjugate nano-biosystems containing ferritin-like constituents. In this work, ferritin was investigated both numerically by all-atom molecular dynamics (MD) simulations using the GROMACS tool, and experimentally by Raman spectroscopy. Molecular dynamic simulations of a model system comprising iron ions (Fe²⁺) and a ferritin trimer expressing a three-fold channel responsible for the ion transport, have revealed a quick entering of ions in the channel. The transit was found to be driven by both electrostatic charge of ferritin, and interaction between the ions. Exit (expulsion) of an iron ion from the channel was observed at a condition that at least one more ion is present in the channel. Otherwise, a single ion may remain in the channel for a long time without exiting. Raman characterization of an iron-loaded ferritin solution revealed pronounced bands attributable to iron, as expected. The study of molecular mechanisms involved in the iron ion transit elucidates the pathways of iron uptake and release in ferritin.

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