| Abstract: | The R-form lipopolysaccharide (LPS) from Klebsiella strain LEN-111 (O3-:K1-) forms a hexagonal lattice structure with a lattice constant of 14 to 15 nm when it is precipitated by addition of two volumes of 10 mM MgCl2-ethanol. The stability of this hexagonal lattice structure in long-term incubation at 4 C was investigated. The hexagonal lattice structure was stable for at least 220 days when the LPS was suspended in distilled water, but it had been disintegrated into a rough mesh-like structure when the LPS was suspended in 50 mM tris(hydroxymethyl)aminomethane (Tris) buffer, pH 8.5, at 4 C for 60 days. Half of the Mg bound to the LPS was released when the LPS was suspended in Tris buffer for 60 days, whereas Mg was not released when it was suspended in distilled water even for 220 days. By contrast, it was stable for at least 220 days in Tris buffer containing 5 mM MgCl2. The LPS suspended in Tris buffer for 60 days, at which time the structure had been disintegrated, could be restored to the original hexagonal lattice structure within 24 hr by addition of 5 mM MgCl2. From these results it is concluded that the hexagonal lattice structure of the LPS retains long-range stability if Mg bound to the LPS is not released from the LPS. |
