All the enzymes of Krebs cycle, fatty acid synthesis and amino acid synthesis are found in matrix but succinic dehydrogenase and cytochrome oxidase are present on inner membrane of mitochondria. The mitochondrial inner membrane contains enzymes of electron transport pathway ie, NAD, FAD, diphospho pyredine nucleotide dehydrogenase, ubiquenone or coenzyone Q10, copper and iron; ATP synthase, succinate dehydrogenase β− hydroxybutyrate dehydrogenase etc. Mitochondrial matrix contains malate dehydrogenase-isocitrate dehydrogenase, fumarase, aconitase, citrate synthase, α− keto acid dehydrogenase, β− oxidation enzymes, etc.