Influence of Magnesium and Manganese on Some Biological and Physical Properties of Tetracycline

Publisher Website
Google Scholar
Abstract
Accumulation of 3 H-tetracycline in nonproliferating cells of susceptible and resistant strains of Escherichia coli and Staphylococcus aureus in tris(hydroxymethyl)aminomethane (Tris) buffer (10 m m , p H 7.5) was significantly decreased in the presence of 5 to 40 m m MgCl 2 and increased in the presence of 5 to 10 m m MnCl 2 . When the bacteria first accumulated 3 H-tetracycline in plain Tris·HCl, and the metal salts were thereafter added, a prompt decrease or increase in radioactivity of the cells was observed after the addition of Mg 2+ or Mn 2+ , respectively. In phosphate buffer (10 m m , p H 7.5), the effect of Mg 2+ was delayed. Three minutes after addition of 3 H-tetracycline, uptake was as in the control cell suspension, but thereafter it dropped rapidly. When 3 H-tetracycline was incubated with Mg 2+ before addition to the bacterial suspension, uptake was scarcely measurable. The addition of Mg 2+ to growing cultures of S. aureus and E. coli caused a marked decrease in susceptibility; in contrast, no increase in susceptibility could be demonstrated when Mn 2+ was added. It was also demonstrated that Mg 2+ and Mn 2+ had distinct influences on the absorption spectrum, the optical rotatory dispersion, the circular dichroism, and the lipid solubility of tetracycline.

This publication has 32 references indexed in Scilit: