Boosting the stability of β-galactosidase immobilized onto soy-protein isolate-glutaraldehyde-functionalized carrageenan beads

Uncontrolled enzyme-immobilizer interactions were evident after immobilizing beta-galactosidase onto soy-protein isolate-glutaraldehyde-functionalized carrageenan beads. Such interactions triggered shortcomings in the immobilized beta-galactosidase (i beta GL) thermal and storage stabilities. The thermal stability of the i beta GL was somewhat lesser than that of the free beta GL. Moreover, the i beta GL suffered an initial sharp fall-off in its activity after storing it. Thus, approaches were adopted to prevent the occurrence of such uncontrolled enzyme-immobilizer interactions, and accordingly, boost the stability of the i beta GL. These approaches involved neutralizing the covalently reactive GA entities via glycine and also altering the functionalizing GA concentrations. Nonetheless, no improvement was recorded in the i beta GL thermal stability and this indicated that the uncontrolled enzyme-immobilizer interactions were not mediated via GA. Another approach was then attempted which involved treating the i beta GL with lactose. The lactose-treated i beta GL (LT-i beta GL) presented superior thermal stability as was verified from its smaller k(d) and bigger t(1/2) and D-values. The LT-i beta GL t(1/2) values were 5.60 and 3.53 fold higher than those presented by the free beta GL at 62 and 65 & DEG;C, respectively. Moreover, the LT- i beta GL presented loftier & UDelta;G than did the free beta GL. The storage stability of the LT- i beta GL was also superior as it offered 100.41% of its commencing activity on its 43rd storage day. Thus, it could be concluded that lactose prevented the uncontrolled enzyme-immobilizer interactions. Finally, advantageous galacto-oligosaccharides (GOS) were prepared via the i beta GL. The GOS were then analyzed with mass spectrometry, and it was shown that their degree of polymerization reached up to 7.