Purification and Characterization of a β-NAcetylhexosaminidase from Wheat Bran and Its Applicability to Biocontrol of Fusarium solani

N-acetyl-β-D-hexosaminidase was purified from wheat bran and characterized. The purified enzyme showed two protein bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) with molecular mass of 75 and 78 kDa. The enzyme exhibited optimum pH and temperature at 5.0 and 50oC, respectively. The enzyme was active on the substrates of p-nitrophenyl-Nacetyl-β-D-glucosaminide (pNP-GlcNAc) and p-nitrophenyl-Nacetyl-β-D-galactosaminide (pNP-GalNAc), whereas inactive on pNP-β-D-glucopyranoside, pNP-β-D-galactopyranoside, swollen chitin, and colloidal chitin, suggesting high substrate specificity. The enzyme activity for pNP-GlcNAc was stable at pH 3–6 and under 50oC. The Km, Vmax and Kcat for pNP-GlcNAc were 0.014mM, 0.05 μmol/min, and 3.01×106 min−1, respectively. The enzyme could be completely inhibited at 1–10 mM HgCl2 and AgNO3,suggesting that the intact thiol group is essential for activity. β-NAcetylhexosaminidase from wheat bran could inhibit the conidial germination and digest the hyphae of Fusarium solani. KCI Citation Count: 1