lipoteichoic-acid and calcium-phosphate--dibasic--anhydrous

3H-labelled lipoteichoic acid was isolated from Lactobacillus casei cells cultured in the presence of [2-3H]-glycerol. The adsorption characteristics of both native and deacylated [3H]-lipoteichoic acid on to hydroxyapatite crystals were determined in 2.0 mM CaCl2, 50 mM Hepes, pH 7.2. The maximum numbers of adsorption sites per unit surface area were 80 +/- 3 and 49 +/- 2 nmol/m2 for native and deacylated lipoteichoic acid, respectively. At low concentrations, which were previously found to stimulate hydroxyapatite growth in a supersaturated solution (1.0 mM CaCl2, 7.5 mM KH2PO4, 50 mM Hepes, pH 7.2), lipoteichoic acid appeared for a large part adsorbed to the crystals, while crystal growth was delayed when there was an excess of unbound lipoteichoic acid in solution. These results suggest that lipoteichoic acid released from plaque bacteria may have dual effects both on the precipitation of calcium phosphate in dental plaque and on the remineralization of lesions in the underlying hard tissues.

Topics: Adsorption; Buffers; Calcium; Calcium Chloride; Calcium Phosphates; Chemical Precipitation; Crystallography; Dental Plaque; Durapatite; Glycerol; HEPES; Humans; Hydrolysis; Lacticaseibacillus casei; Lipopolysaccharides; Minerals; Phosphates; Potassium Compounds; Solutions; Surface Properties; Teichoic Acids; Tritium

The precipitation of Ca-compounds in ageing dental plaque leads to the formation of calculus. Bacterial lipoteichoic acid (LTA) has been discussed as Ca-carrier in this process (Zoon et al., 1989). Therefore in this study, LTA was isolated from oral streptococci and tested for its influence on the precipitation of Ca-phosphate. LTA-containing bacteria, LTA-free bacteria and isolated LTA were added to the reaction mixtures for Ca-phosphate precipitation and the amount of precipitated mineral was measured. LTA-containing cells and, above all, LTA, inhibited Ca-phosphate precipitation in a distinct pH-range just above the acid solubility of the mineral by complexing Ca(2+)-ions. Experiments with Ca-fluoride in place of Ca-phosphate showed that LTA did not affect the precipitation of this mineral.

Topics: Calcium Fluoride; Calcium Phosphates; Dental Calculus; Dental Enamel Solubility; Dental Plaque; Hydrogen-Ion Concentration; Lipopolysaccharides; Streptococcus mutans; Teichoic Acids