Diagnostic application of mitochondrial enzymes and isoenzymes

Evolutionary, topological and metabolic aspects of mitochondrial enzymes and isoenzymes are reviewed, and the structural and functional heterogeneity of mitochondria is demonstrated. Primary deficiencies of mitochondrial enzymes are described and the need for their proper recognition is illustrated. Species differences of secondary dysfunction of mitochondrial enzymes are shown. The release of mitochondrial enzymes is compared to that of cytosolic enzymes from liver and heart muscle cells and the diagnostic significance of assays of mitochondrial enzymes in serum is evidenced. Possible mechanisms of mitochondrial enzyme release from cells and unresolved questions pertaining to this process are discussed in light of potential diagnostic utility of mitochondrial enzymes in serum.