Thermostable beta-galactosidase from Escherichia coli transformant containing the enzyme gene from Pyrococcus woesei was immobilized at pH 5.5 on silica gel by crosslinking with transglutaminase. The obtained preparations had a specific activity of 11.573 U/g of support at 70C using oNPG as a substrate. The optimum pH and temperature for immobilized beta-galactosidase activity were 5.5 and 95C. The immobilized enzyme is stable at the temperatures close to the optimal value and the residual activity for oNPG hydrolysis of the preparations incubated 1 h in 0.1 M phosphate citrate buffer (pH 5.5) at 100C was about 70% of the initial value.
Jozef Synowiecki, Katedra Chemii, Technologii i Biotechnologii Zywnosci, Wydzial Chemiczny, Politechnika Gdanska, ul. Gabriela Narutowicza 11/12, 80-952 Gdansk, Poland