Revision as of 06:11, 12 October 2023

IsPETaseQ119F/W159H-Linker-CBM11-6xHis Tag

IsPETase is a hydrolase produced by Ideonella sakaiensis that degrades PET. Q119F and W159H double mutants have the highest PET degradation activity among double mutants, and CBM11 is the most hydrophobic domain, so plasmids containing this composite element are constructed.

Characterization

1. HPLC

After protein purification, an enzymatic reaction is performed to measure the activity of the enzyme. The substrates used are PET film, PET powder and filter cloth, under the action of IsPETase, PET powder is broken down into TPA and MHET. Determine the volume of purified enzyme solution required for 500 μL of the reaction system based on protein concentration. At 37 °C, it reacted with PET film, PET powder and filter cloth for 48h, and after the end the reaction solution was analyzed by high performance liquid chromatography, the liquid phase result of 6min corresponds to TPA, and the liquid phase result of 8min corresponds to MHET. Through the standard curve, the peak area of the product output by the liquid phase instrument is converted into the product concentration, such as Fig.1. Fig.1 500nM WT and IsPETase^Q119F/W159H - Linker-CBM11 reaction with PET film, PET powder, filter cloth at 37 °C for 48 h TPA, MHET concentration.

Analysis of the results At 37°C,the substrate is PET film, IsPETase^Q119F/W159H-Linker-CBM11 product concentration is about 6 times that of WT; the substrate is PET powder, IsPETase^Q119F/W159H-Linker-CBM11 product concentration is about 5 times that of WT; the substrate is filter cloth, IsPETase^Q119F/W159H-Linker-CBM11 product concentration is about 6 times that of WT.

2. SEM

After 48h degradation, we observed the changes on the surface of the PET film under an electron microscope.

Fig.2 (A) SEM images of PET films degraded by the enzyme-free system for 48h; (B) SEM images of PET films degraded by IsPETase for 48h; (C) SEM images of PET films degraded by IsPETase^Q119F/W159H - CBM11 for 48h.

By Fig.2, the degree of degradation of the PET material can be reflected by the degree of surface depression in the SEM image. Since (A) was only immersed in buffer solution for 48h without degradation by enzyme addition solution, it presents a smooth surface in the SEM image. (B) is the effect after 48h of WT degradation, a slight depression can be seen on the surface, but the degree of depression is not obvious. (C) is the effect of IsPETase^Q119F/W159H - CBM11 after 48h of degradation, it can be seen that some areas of depression are more obvious than the effect of WT.

Fig.3 (A) SEM images of the degradation of industrial filter cloth by the enzyme-free system for 48 h; (B) SEM images of the degradation of industrial filter cloth by IsPETase for 48 h; (C) SEM images of the degradation of industrial filter cloth by IsPETase^Q119F/W159H - CBM11 for 48 h. The degradation degree of the PET material can be reflected by the roughness of the surface in the SEM images.

Sequence and Features