The role of bivalent ions in the inactivation of bacteriophage ϕ X174 by lipopolysaccharide from Escherichia coli C

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Abstract
The need for Ca2+ in the inactivation of bacteriophage .vphi.X174 by lipopolysaccharide from Escherichia coli C was confirmed. Ca2+ could be replaced almost completely by Na+, but the concentration of Na+ needed was greater by more than an order of magnitude. Other bivalent ions cuased inactivation in the same way as Ca2+, and the degree of inactivation varied according to the ion. At 50% inactivation of bacteriophage, the relation between the concentrations of NaCl and of bivalent or tervalent ions (Mx+) fitted the conception that NACl was neutralizing electrostatic repulsion between virus and lipopolysaccharide by an inonic-strength effect: that is, log[Mx+] varies inversely with .sqroot. [NaCl]. The variation in effect of bi- and ter-valent ions and the low concentration needed show that this is not an ionic-strength effect but likely to invovle binding to more than one site.