Activity and subcellular distribution of some mitchondrial enzymes in skeletal muscle. I. Light and dark bovine and porcine muscles

Abstract

In different bovine and porcine muscles (Longissimus dorsi, Semimembranaceus; Diaphragma) the extractable activities of aconitase (AC), F-marase (FU), malate dehydrogenase (MDH) and succinate dehydrogenase (SDH) were determined. The subcellular distribution of these enzymes within the tissue was eludicated by determination of the enzyme activities in the press juice of the intact muscle tissue. The activity of SDH was additionally determined in the muscle homogenates. SDH was found to be almost completely associated with cellular structures. Less than 10% of the total FU activity was present in the soluble state. Slightly more than 20% of the total AC was localized within the sarcoplasma. The subcellular distribution of these enzymes was influenced by muscle type and animal species. The MDH of porcineLongissimus dorsi andSemimembranaceus was present completely in soluble state; in the other muscles only about 50% of the total MDH was localized within the sarcoplasma. A. positive correlation was found between the activities of AC, FU and SDH and the myoglobin content of the muscles. This relationship was more pronounced in porcine muscles than in bovine muscles. With MDH, no such correlation was found for bovine muscles, but a negative correlation between MDH and myoglobin content existed for porcine muscles. The differences between bovine and porcine muscles seem to be related also to other factors besides the metabolic type of muscles determined by the myoglobin content.