Studies of lysosomal enzymes in fish muscle tissue. III. Intracellular distribution of enzymes and particle properties of lysosomes in mackerel muscle tissue.

he present work was undertaken to investigate the intracellular distribution of the enzymes such as cytochrome C oxidase (the mitochondrial. marker), β-glucuronidase, β-N-acetylglucos-aminidase, acid phosphatase and cathepsin D (the lysosomal markers), catalase (the peroxisomal marker) and alkaline ghosphatase (the microsomal marker) in white and red muscles of mackerel according to differential centrifugation. Some properties of both muscle lysosomes were also examined. In the white muscle, the highest relative specific activities of cytochrome C oxidase, and the four lysosomal enzymes, catalase and alkaline phosphatase were found in the mitochondrial and lysosomal fractions, respectively. In the red muscle, the highest relative specific activities of cytochrome C oxidase, the four lysosomal enzymes, and catalase and alkaline phosphatase were in the mitochondrial, lysosomal and microsomal fractions, respectively. The buoyant densities of white and red muscle lysosomes were determined to be 1.03g/ml by iso-osmotic self-generating gradients composed of modified colioidal silica (Percoll), but about the same amount of lysosomes having higher buoyant density, ahout 1.04g/ml, was found in red muscle. The maximum stability of the muscle lysosomes was observed in sucrose over 0.2M and at pH 7. By incubating at 37°C, the fragility of red muscle lysosomes was significantly effected as compared with the white muscle lysosomes. The difference in fragility between red and white muscle lysosomes of mackerel was greater than that of carp.