The C-terminal catalytic domain of tobacco N-acetylglucosaminyltransferase I fused to maltose-binding protein was produced in Escherichia coli as a soluble form with significant activity. The protein was affinity-purified using amylose resin, and its enzymatic properties were investigated, including its divalent cation requirements, optimal temperature, optimal pH, and substrate specificity. (C) 2009, The Society for Biotechnology, Japan. All rights reserved.