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Effect of lactoperoxidase system on glucosyltransferase D of Streptococcus mutans
X Yu1, V Loimaranta, M Lenander-Lumikari
1Department of Stomatology, 1st Clinical College, Harbin Medical University, No. 23, Youzheng Street, Nangang District, Harbin-150001, Heilongjiang Province, P. R. China.
Objective:
To investigate the effects of the peroxidase system (LP, H2O2, SCN) and its components on the activity of glucosyltransferase D (GtfD) originating from Streptococcus mutans (S. mutans).
Methods:
GtfD was incubated in buffered-KCl assay mixture that contained 20 microM dextran and 100 mM sucrose including 14C-glucose. The activity of GtfD was measured with a scintillation counter. The effects of lactoperoxidase system and its components on GtfD activity were examined by incubating different components separately and together with GtfD.
Results:
The lactoperoxidase system-generated hypothiocyanite (OSCN) had no effect on the activity of streptococcal GtfD, while the lactoperoxidase enzyme inhibited GtfD. The ratio between the 2 enzymes, LP and GtfD, was important for the inhibition. However, if LP was combined with its substrates, SCN and/or a high concentration of H2O2, it enhanced the activity of GtfD.
Conclusion:
Peroxidase-generated antimicrobial agent HOSCN/OSCN is not inhibitory against GtfD, whereas low concentrations of the LP-enzyme inhibit GtfD.