Microsome assay

Microsome assay (from the Greek. mikros - small and soma - the body) - microsome faction, or fraction of light granules obtained by the differential centrifugation (at high speeds) homogenates of different cells after deposition of cell nuclei and mitochondria. Fraction of microsomes, accounting for about 15-20% of all cell mass, may be heterogeneous and contain as impurities fragments of mitochondria (see), membranes, cytoplasm (see), glycogen, etc. This fraction is much richer in content RNA: it is concentrated up to 50 - 60% of total RNA cells. In microsome faction also contains large amounts of proteins and phospholipids. Fraction of microsomes more active than the others in respect of protein synthesis. The sizes of the components volatile and fluctuate within the range of 50-150 MMK. In the intact cells in the study them in electronic microscope is not found other structures of this size and with an equally clear morphology. Apparently, the microsomal fraction is an isolated areas of cytoplasm, its parts, consisting of membrane and granular components typical of elastoplastic.
Lipoproteidnyi component of microsomes is a membrane elements elastoplast, while granular - ribosome (this elementary ribonucleoprotein particles, on which the synthesis of proteins). When processing a fraction of microsomes detergents (see), solvent lipoproteidnyi membrane (dezoksiholatom), ribosomes are discharged with membranes and can be obtained in the form of pure fractions of ribosomes by centrifugation at the accelerations above 100 000 g. The activity of the faction M in respect of the synthesis of the protein is determined by the activity of ribosomes. Cm. also the Cell.