Purification and characterization of a <Emphasis Type="Italic">N</Emphasis>-acetylglucosaminidase produced by <Emphasis Type="Italic">Talaromyces emersonii</Emphasis> during growth on algal fucoidan

A β-N-acetylglucosaminidase produced by a novel fungal source, the moderately thermophilic aerobic ascomycete Talaromyces emersonii, was purified to apparent homogeneity. Submerged fermentation of T. emersonii, in liquid medium containing algal fucoidan as the main carbon source, yielded significant amounts of extracellular N-acetylglucosaminidase activity. The N-acetylglucosaminidase present in the culture-supernatant was purified by hydrophobic interaction chromatography and preparative electrophoresis. The enzyme is a dimer with molecular weight and pI values of 140 and 3.85, respectively. Substrate specificity studies confirmed the glycan specificity of the enzyme for N-acetylglucosamine. Michaelis-Menten kinetics were observed during enzyme-catalyzed hydrolysis of the fluorescent substrate methylumbelliferyl-β-D-N-acetylglucosaminide at 50°C, pH 5.0 (K_m value of 0.5 mM). The purified N-acetylglucosaminidase displayed activity over broad ranges of pH and temperature, yielding respective optimum values of pH 5.0 and 75°C. The T. emersonii enzyme was less susceptible to inhibition by N-acetylglucosamine and other related sugars than orthologs from other sources. The enzyme was sensitive to Hg²⁺, Co²⁺ and Fe³⁺.