Purification and properties of an α-(1→3)-glucanase (EC 3.2.1.84) from Trichoderma harzianum and its use for reduction of artificial dental plaque accumulation

Extracellular alpha-(1 -> 3)-glucanase (mutanase, EC 3.2.1.84) produced by Trichoderma harzianum CCM F-340 was purified to homogeneity by ultrafiltration followed by ion exchange and hydrophobic interaction chromatography, and final chromatofocusing. The enzyme was recovered with an 18.4-fold increase in specific activity and a yield of 4.3%. Some properties of the alpha-(1 -> 3)-glucanase were investigated. The molecular mass of the enzyme is 67 kDa, as estimated by SDS/PAGE, its isoelectric point 7.1, and the carbohydrate content 3%. The pH and temperature optima are 5.5 and 45 degrees C, respectively. The enzyme is stable over a pH range of 4.5-6.0 and up to 45 degrees C for 1 h. The K-m and V-max under standard assay conditions are 0.73 mg/ml and 11.39 x 10(-2) mu mol/min/mg protein, respectively. The enzyme activity is stimulated by addition of Mg2+ and Na+, and significantly inhibited by Hg2+. The alpha-(1 -> 3)-glucanase preparation preferentially catalyzed the hydrolysis of various streptococcal mutans and fungal alpha-(1 -> 3)-glucans. The 20-residue N-terminal sequence of the enzyme is identical with those of other alpha-(1 -> 3)-glucanases from the genus Trichoderma, and highly similar to those from other fungi. The purified alpha-(1 -> 3)-glucanase was effective in preventing artificial dental plaque formation. The easy purification from fermentation broth and high stability, and the effective inhibition of oral biofilm accumulation make this alpha-(1 -> 3)-glucanase highly useful for industrial and medical application.