Comparative studies on enzymatic changes and structure of lipases under ultrasound
摘要
The influences of ultrasound pretreatment on the catalytic activity, enzymatic properties and structure of two commercial lipases, Novozym51032 (lipase N) and Palatase20000L (lipase P), were studied by comparing the lipase kinetic and thermodynamic parameters of lipase and protein structure analysis. The experimental results showed that lipase N showed enhanced activity, while lipase P showed reduced activity under identical ultrasound conditions. Furthermore, the Vmax of lipase N increased and the free energy (ΔG) decreased, whereas lipase P showed the opposite change. Both lipases underwent hydrophobic group exposure, yet the changes in their secondary structures were in opposition to one another. The intermolecular aggregates of lipase N were fragmented into small aggregates by ultrasound, a phenomenon not observed with lipase P. This result demonstrates that ultrasound stimulation enhances lipase activity primarily through the modulation of enzyme secondary structure and the disruption of intermolecular aggregates. Moreover, ultrasound treatment has been demonstrated to enhance the storage stability of the enzyme. These results demonstrate the potential value of ultrasound treatment in optimizing enzymes and bioprocesses.