Lactoperoxidase Inhibits Glucosyltransferases from <i>Streptococcus mutans </i>in vitro

Abstract

This study examines the possible effect of the antimicrobial peroxidase system on the activity of streptococcal glucosyltransferases B, C and D (GtfB, GtfC and GtfD), either in solution (GtfB and GtfC) or when adsorbed to hydroxyapatite (GtfC and GtfD) at pH 6.5. The lactoperoxidase (LP) system (LP, H₂O₂, SCN^–) had no effect on the activity of dissolved GtfC, but the activity of dissolved GtfB was enhanced. The LP system, however, strongly inhibited the activities of both GtfC and GtfD in their adsorbed form. LP enzyme, without its substrates, inhibited all three Gtf enzymes: GtfB and GtfC in concentrations between 10 and 100 µg/ml in liquid phase and adsorbed GtfC and GtfD in concentrations between 25 and 50 µg/ml. This inhibition was in part abolished in liquid phase, but not in solid phase, if the substrates of LP were added. This study shows that the lactoperoxidase system can exert inhibitory activity against streptococcal Gtfs without generating oxidizing agents.

Biology of <i>Streptococcus mutans-</i>Derived Glucosyltransferases: Role in Extracellular Matrix Formation of Cariogenic Biofilms

“…In addition, Gtfs also bind to other components of the salivary pellicle such as salivary peroxidase, amylase and lysozyme [Korpela et al, 2002; Hannig et al, 2005; Kho et al, 2005]. Available data shows clearly that Gtfs interact with salivary amylase in pellicle [Vacca-Smith et al, 1996a] inhibiting activity and blocking adsorption of salivary amylase to HA [Hannig et al, 2005].…”

“…Available data shows clearly that Gtfs interact with salivary amylase in pellicle [Vacca-Smith et al, 1996a] inhibiting activity and blocking adsorption of salivary amylase to HA [Hannig et al, 2005]. Lactoperoxidase in the absence of substrates, which is structurally and enzymatically similar to salivary peroxidase, inhibits all 3 Gtf enzymes in solution or adsorbed to sHA beads [Korpela et al, 2002]. The presence of lysozyme reduced the activity of GtfB in solution and on a surface but was without apparent effect on the structure of glucan formed [Kho et al, 2005].…”

Enzymes in the acquired enamel pellicle

“…As an agonist of lysozyme, peroxidase inhibits the adherence of S. mutans to hydroxyapatite (78, 88, 89). However, peroxidase also inhibits glucosyltransferase immobilized in pellicles on hydroxyapatite (90).…”

The Significance of Lactoperoxidase System in Oral Health: Application and Efficacy in Oral Hygiene Products

“…Cawley et al demonstrated that the LPO system together with lactoferrin, lysozyme, and bovine milk immunoglobulins have the ability to inhibit the formation of single-species S. mutans biofilm, whereas, in the case of multispecies biofilms (which more accurately represents biofilms occurring in vivo), its application resulted in the loss of microbial viability without the decrease in biofilm mass [141]. This fact can be explained by the ability of the LPO system to kill microorganisms, but the inability to inactivate glucosyltransferases, i.e., extracellular bacterial enzymes responsible for the synthesis of glucans building a biofilm matrix [142].…”