The effect of antibacterial compounds on glucosyltransferase activity from Streptococcus mutans.

The effect of several plaque-inhibiting and/or antibacterial compounds on glucan synthesis by glucosyltransferases purified from the cariogenic bacterium Streptococcus mutans strain 6715 was determined. Drugs were tested at concentrations of 0.2–2.0 mM at pH values between 6.5 and 6.8. Bis-biguanides, quaternary ammonium salts and aliphatic amines were found to be potent inhibitors of enzyme activity. The strong anionic detergent, sodium lauryl sulphate and the phenol derivative, hexylresorcinol, also caused significant inhibition. Basic nitrogen compounds lacking a functional hydrophobic group were less inhibitory or stimulated enzyme activity. Both electrostatic and hydrophobic interactions appear to be occurring between the cationic test-agents and the glucosyltransferases, with hydrophobic interaction being more important for enzyme inhibition.