Covalent immobilization of recombinant L-asparaginase from Geobacillus kaustophilus on ReliZyme supports for mitigation of acrylamide

Abstract

In this study, a new recombinant L-asparaginase from Geobacillus kaustophilus was covalently immobilized on ReliZyme EA403 (Relizyme/EA@GkASNase) and ReliZyme HA403 (Relizyme/HA@GkASNase) supports, and the free and immobilized L-asparaginases were used for their acrylamide mitigation performances in a food model system. The immobilization was confirmed by fourier-transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy analysis. The optimum pH was determined as 8.5 for all the free and immobilized L-asparaginase samples. The optimum temperature was determined as 55 ? for the free enzyme and 60 ? for both the immobilized samples. The thermal stability of L-asparaginase was increased by 17.6 and 37.2 folds at 60 ? for Relizyme/EA@GkASNase and Relizyme/HA@GkASNase, respectively. Relizyme/EA@GkASNase and Relizyme/HA@GkASNase showed 16% and 43% of the catalytic efficiency of free GkASNase. The acrylamide mitigation performances of free and immobilized L-asparaginase samples were investigated using the L-asparagine-starch food model system and the formed acrylamide was completely mitigated in 1 h for all the L-asparaginase samples. Both the immobilized L-asparaginase samples retained at least 80% of their activities after five reuses. Hence, the immobilized GkASNase preparations can be potentially used in heat-treated food industries to remove acrylamide.