Electron microscope observations on the structure of microsomal particles from Escherichia coli

摘要: Microsomal particles from E. coli are known to exist in a number of different stable forms, depending foremost on the concentration free magnesium ions, and characterized by sedimentation coefficients 100 s, 70 50 s 30 s. These identified each case analysis, have been investigated electron microscopy, using both negative positive staining. Using staining it was found that consisted two joined together as dimer. The could be seen contain subunits unequal size with well-marked cleft between them, smaller were apposed. resemble closely larger sub-units particles. In addition, purified particles, when transferred medium which stable, formed dimers coefficient about 81s. not regular polyhedral form, contrast some small spherical viruses. appeared very approximately dome-shaped. had flatter form rather irregular outline. subunit fit like an overlapping cap flattened face one. When microsomal stained uranyl acetate (which many situations appears act preferential stain for nucleic acids) they showed complex internal structure, but no indication No evidence existence protein shell around acid core again