Title

The postmortem potential of mitochondria and its effects on myoglobin forms and stability

Date of Completion

January 2005

Keywords

Agriculture, Food Science and Technology

Degree

Ph.D.

Abstract

The form and redox stability of the heme protein myoglobin (Mb) are affected by many factors, including partial oxygen pressure, metmyoglobin (MetMb) reducing activity, and lipid oxidation. Mitochondria are closely associated with Mb in living cells and have the potential to affect its redox stability. This research was conducted to determine the postmortem alterations of mitochondria and the effects of mitochondrial respiration on Mb redox forms and stability, to characterize mitochondria-dependent MetMb reduction, and to investigate the potential relationship between mitochondrial lipid oxidation and oxymyoglobin (OxyMb) oxidation. Morphological integrity of mitochondria decreased with time postmortem; however, some ability to consume oxygen was retained. Mitochondrial respiration resulted in the conversion of OxyMb to MetMb or deoxymyoglobin and this was dependent on mitochondrial density, oxygen and substrate availability, and pH. Mitochondrial electron transfer had the potential to mediate MetMb reduction; however, this ability decreased with time postmortem and was inhibited at low pH. Mitochondrial lipid oxidation appeared to be interrelated with OxyMb oxidation and both processes were inhibited by increased mitochondrial α-tocopherol concentrations. ^