Author : Vilai Santisopasri

Summary : Acid and neutral invertases in sugarcane milled juice were purified six-fold by precipitation with ammonium sulfate at 20-40% saturation and 73-fold by Sephadex, A1 and N1, corresponding to the isoenzymes were observed. Acid invertase A1 has a MW (molecular weight) of 380,000 while neutral invertase N1 has a MW of 66,000. The presence of three minor peaks with neutral invertase activity and multiple MW values suggest aggregation of the neutral enzyme. The major acid and neutral isoenzymes have carbohydrate contents of 23.5% and 22.0%, respectively. The (NH4)2 SO4 purified invertases were completely inhibited by 4mM (millimolar) lauryl sulfate, 20mM metasilicate and 0.2% detergent 'Tide'. both invertases in filtered juice were completely inhibited by 12mM lauryl sulfate, 42mM metasilicate and were 15% inhibited by 0.25% 'Tide'. The acid invertase, whose optimum pH is 5.3, was more strongly inhibited by lauryl sulfate than the neutral enzyme.