Cell wall invertase immobilisation within gelatin gel

Abstract

Yeast cell wall invertase (CWI) was immobilised within 10% gelatin hydrogel. The result of entrapment was the complete immobilisation of all the added CWI. The activity of immobilised biocatalyst was 93 +/- 3 U/g, with activity yield of 30%. The optimum pH was in range of 4.5-5.0 for free and immobilised biocatalyst. The optimum temperature was 60 degrees C for both free and gelatin immobilised CWI. Immobilised CWI was more stable than free CWI above optimum activity temperatures. The K-m of free and immobilised CWI was 35.10 +/- 2.99 mM and 71.45 +/- 3.23 mM, respectively. The V-max, values were estimated as 8.23 +/- 0.24 mM/min and 0.121 +/- 0.002 mM/min, respectively. Immobilised CWI was tested in a batch reactor using 50% sucrose (w/v). After 70 consecutive cycles gelatin immobilised CWI retained 75% of its original activity.