Disintegration of Mg<sup>2+</sup>-Induced Hexagonal Assembly of an R-Form Lipopolysaccharide from <i>Klebsiella pneumoniae</i> by Treatment with CaCl<sub>2</sub>

  • Ito Hideo
    Nagoya University School of Health Sciences
  • Naito Setsuko
    Department of Bacteriology, Nagoya University School of Medicine
  • Kato Nobuo
    Department of Bacteriology, Nagoya University School of Medicine

抄録

R-form lipopolysaccharide (LPS) from Klebsiella pneumoniae strain LEN-111 (O3-:K1-), which was precipitated by the addition of 2 volumes of ethanol containing 10mM MgCl2 for the purification process, ultrastructurally exhibited membrane pieces consisting of an ordered hexagonal lattice structure with a lattice constant of 14 to 15nm. When the R-form LPS was suspended in 50mM tris (hydroxymethyl) aminomethane buffer (at pH 8.5) containing 1mM or higher concentrations of CaCl2 and kept at 4C for 10 hr, the ordered hexagonal lattice structure of the R-form LPS was disintegrated and changed to an irregular rough, mesh-like structure. By treatment with CaCl2, the content of Mg in the LPS was markedly decreased, and conversely, the content of Ca was increased to a level depending upon the concentration of CaCl2. Results indicate that the addition of CaCl2 to suspensions of the Mg-bound R-form LPS result in a tighter binding of Ca2+ to the R-form LPS and the release of Mg2+ from the R-form LPS, and as a consequence, destroys the Mg2+-induced ordered hexagonal lattice structure of the R-form LPS.

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