Fig.7
3.7 Thermostability study
The thermostability of free
enzyme and immobilized enzyme at 50 ℃ was investigated (Fig.8). The
reductive amination activity of the immobilized enzymes has declined
gradually over time. After incubation for 10h, DAADH/ZIF-8/RGO still
retained 53.4% relative enzyme activity and had good thermostability
stability. The residual enzyme activity of DAADH/ZIF-8 system was 37.8%
while the free enzyme was almost inactivated. The results showed that
immobilization improve thermostability stability of DAADH.
The enhancement of thermostability probably due to interaction between
peptide and MOF which may restrict the conformational change of DAADH.
The dissociation of subunit was prevented by cage effect of MOF
immobilization. With large specific surface area, functional diversity
and precise control of the particle size, MOFs are ideal carrier with
biocompatible microenvironments for enzyme immobilization [26, 27].