PARTIAL-PURIFICATION AND CHARACTERIZATION OF SUGARCANE NEUTRAL INVERTASE

Sugarcane neutral invertase (SNI) has been partially purified From mat ure sugarcane stem tissue to remove any potential competing activity. The enzyme is non-glycosylated and exhibits catalytic activity as a mo nomer, dimer and tetramer, most of the activity elutes as a monomer of native M-r ca 60k. The enzyme displays typical hyperbolic saturation kinetics for Suc hydrolysis. It has a K-m of 9.8 mM for Suc and a pH o ptimum of 7.2. An Arrhenius plot shows the energy of activation of the enzyme for Suc to be 62.5 kJ mol(-1) below 30 degrees and - 11.6 kJ m ol(-1) above 30 degrees. SNI is inhibited by its products, with Fru be ing a more effective inhibitor than Glc. SNI is significantly inhibite d by HgCl2, AgNO3, ZnCl2, CuSO4 and CoCl2 but not by CaCl2, MgCl2 or M nCl2. SNI showed no significant hydrolysis of cellobiose or trehalose. (C) 1998 Elsevier Science Ltd. All rights reserved.