The Role of HOSCN in the Oxidation of Proteins and Cellular Damage in Atherosclerosis

Abstract

Myeloperoxidase forms the reactive oxidants hypochlorous acid (HOCl) and hypothiocyanous acid (HOSCN). While HOCl is an extremely reactive oxidant that causes extensive damage to all manner of biomolecules, HOSCN reacts preferentially with protein thiols. This targeting of thiols can lead to protein inactivation and inhibition, and has led to HOSCN being implicated in the alteration of numerous cellular redox pathways. This Thesis compares the ability of HOCl and HOSCN to form reversibly oxidised cysteine products in murine J774A.1 macrophages, examining changes to the protein thiol levels and the manner of oxidised cysteine products formed in the cells upon oxidation, with changes to the cellular chemistry observed via WB analysis, FTIR and Raman microscopy. Further studies employ real-time analysis into the functional changes in metabolism of J774A.1 cells after HOSCN treatment. Results show that HOSCN is able to affect macrophage glucose metabolism via the oxidation of glycolytic proteins. The oxidation of glycolytic proteins causes a reduction in the glycolytic end product, pyruvate, and extend to mitochondrial oxidative phosphorylation, mitochondrial permeability transition pore function and ATP production. In summary, the studies of this Thesis may be significant in understanding the inflammatory process of atherosclerosis, especially in cigarette smokers, who have elevated levels of thiocyanate, the parent ion of HOSCN in their plasma.