The R-form lipopolysaccharide from
Klebsiella pneumoniae strain LEN-111 (O3-:K1-), from which cationic material had been removed by electrodialysis, was previously shown to form a hexagonal lattice structure with the lattice constant of 14 to 15nm when suspended in 50mM tris(hydroxymethyl)aminomethane buffer at pH 8.5 containing 10mM Mg
2+. Under this experimental condition, effects of other divalent metal cations on the hexagonal assembly of the electrodialyzed LPS were compared with that of Mg
2+. The Zn
2+, Hg
2+, Cu
2+, and Ni
2+ could produce essentially the same hexagonal lattice structure with the lattice constant of 14.5 to 15.0nm as that formed with Mg
2+. The Cd
2+, Co
2+, and Fe
2+ produced the hexagonal lattice structure with the lattice constant of 15.5 to 16.0nm, and Ba
2+ Sr
2+, and Ca
2+ produced that with the lattice constant of 18 to 19nm. In addition, the hexagonal lattice structures formed with the latter three cations were less orderly than those formed with the other cations. When the higher concentrations of Ba
2+, Sr
2+, and Ca
2+ were used, the lattice constants were not shortened. The length of lattice constants of the hexagonal lattice structures formed with the divalent cations did not relate to the quantity of the cations bound to the LPS. Among the divalent cations tested, Hg
2+ was bound to the LPS in the smallest amount (its atomic ratio to P, 0.07), and Zn
2+ and Fe
2+ were bound in very large amounts (their atomic ratios to P, 2.94 and 8.28, respectively).
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