Extracellular α-(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 α-(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°C, respectively. The enzyme is stable over a pH range of 4.5-6.0 and up to 45°C for 1 h. The Km and Vmax under standard assay conditions are 0.73 mg/ml and 11.39 x 10-2 µmol/min/mg protein, respectively. The enzyme activity is stimulated by addition of Mg2+ and Na+, and significantly inhibited by Hg2+. The α-(1 → 3)-glucanase preparation preferentially catalyzed the hydrolysis of various streptococcal mutans and fungal α-(1 → 3)-glucans. The 20-residue N-terminal sequence of the enzyme is identical with those of other α-(1 → 3)-glucanases from the genus Trichoderma, and highly similar to those from other fungi. The purified α-(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 α-(1 → 3)-glucanase highly useful for industrial and medical application.
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