Abstract
Invertase from Saccharomyces cerevisiae was activated by periodate treatment and further reacted with ethylenediamine/sodium borohydride. Carboxymethylcellulose was then attached to ethylenediamine-modified invertase using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide as coupling agent. The modified enzyme contained 3.5 mol of polysaccharide per mol of holoenzyme, and retained about 56% of the initial invertase activity. The thermostability of invertase increased from 64 to 70° C, the thermal inactivation at different temperatures ranging from 60 to 70° C was markedly reduced for polymer-modified enzyme. An increase of 9.1 kJ mol−1 in activation free energy of inactivation was determined for invertase after modification. Functional stability was increased for carboxymethylcellulose-invertase complex in the range of pH between 2.0 and 12.0. The conjugate was also more resistant to denaturation by 6 M urea solution.
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