Role of solvent access to myoglobin and hemoglobin: A unifying mechanism of oxidative deterioration in muscle foods

Major goalsInnovative strategies to inhibit discoloration and off-flavor in muscle foods have been limited due to a lack of understanding in the basic mechanisms by which heme proteins auto-oxidize and oxidize lipids. This is partly due to analytical difficulties in measuring reactions that occur in the heme microenvironment. This project will utilize expertise in engineering, heme protein chemistry, and analytical biochemistry to measure solvent access to the heme microenvironment in relation to oxidative degradation. The goal is to determine if a unifying mechanism for oxidative degradation of heme proteins occurs in systems that vary in pH, heme protein type, and small molecules that covalently bond to selected heme proteins. Specifically, solvent access to the distal crevice is expected to facilitate auto-oxidation while solvent access to the proximal crevice will facilitate heme loss that leads to oxidation of lipids. It is anticipated that results from this work will provide a focal point for novel and cost-effective antioxidant strategies. The specific objectives in relation to auto-oxidation, heme loss and lipid oxidation measurements are below. Objectives:Determine solvent access to the distal and proximal heme crevices of bovine Mb and bovine Hb at pH 5.6 compared to pH 6.3.Determine solvent access to the distal heme cavity of bovine Mb compared to Mb containing covalently bound HNE.Determine solvent access to the distal and proximal heme cavity of turkey HbA compared to turkey HbA containing covalently bound caffeic acid.Determine solvent access to the distal and proximal heme cavities of bovine Mb compared to bovine Hb and bovine Hb to trout IV Hb.