Quantum chemistry-based verification of antioxidative action of iodide in mitochondria

Abstract

Background: In view of the well-known health-care qualities of aqueous potassium iodide (KI), quantum chemistry-based molecular modeling, i.e., density functional theory-based molecular modeling (DFT/MM) is undertaken to understand how iodide ion (I-) shows antioxidative properties on aqueous phosphorylation process in mitochondria (mt) of alive cells. Materials and methods: We perform DFT/MM equivalent to the quantum mechanics/molecular mechanics (QM/MM) method, by using the B3LYP exchangecorrelation function and the 6–31G(d) basis set with Spartan’18 (Wavefunction, Inc. Irvine, CA). Results: Iodide ion (I-) is in equilibrium with hydrogen iodide (HI), being oxidized to hypoiodous acid (HOI) by ground state oxygen (O2) or by hydrogen peroxide (HOOH) in aqueous systems. DFT/MM also verifies that van der Waals force (vdW) induces van der Waal (vdW) aggregation of hypoiodous acid (HOI) with phenylalanine, resulting in giving tyrosine, and that vdW works strongly on aggregation of tyrosine with HOI, leading to formation of 2,6-diiodotyrosine via 2-iodotyrosine. 2,6-Diiodotyrosine as homolog of thyroid hormones T4 is validated to show antioxidative action to evil active oxygen in mt, i.e., HOOH and hydroxyl radical.