Thermostable Protease Variants for Polylactic Acid Degradation
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Solution Overview
Problem
There is a need for proteases with improved thermostability to enhance the efficiency of degrading and recycling processes of plastic products, particularly polylactic acid, as existing proteases are not sufficiently stable at elevated temperatures required for industrial processes and environmental degradation.
Innovation Solution
Development of protease variants with specific amino acid sequence modifications, such as substitutions and insertions, that exhibit increased thermostability and maintain degrading activity at temperatures between 40°C to 90°C, particularly at 70°C +/- 5°C, suitable for degrading polyester and plastic materials like polylactic acid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If proteases are used for degrading polyester and plastic materials at elevated temperatures, then degradation efficiency is improved, but protease stability deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying amino acid sequences at specific positions (e.g., positions 169, 172, 176, 262, 266) to alter the protease's thermal stability parameters. These sequence modifications enable the enzyme to maintain stability at elevated temperatures while preserving degradation activity, thus resolving the contradiction between productivity and reliability.
Solution Approach 2:
The invention creates composite protease variants by combining multiple amino acid substitutions (e.g., A169C + T176C, N262C + T266C) to achieve synergistic effects. This composite approach allows the protease to simultaneously gain thermostability and maintain catalytic efficiency at high temperatures, addressing both degradation efficiency and enzyme stability requirements.
2Speed
If proteases are used in industrial processes at high temperatures, then process speed is improved, but enzyme half-life deteriorates
Solution Approach 1:
The patent modifies kinetic and stability parameters of the protease through amino acid substitutions. These changes allow the enzyme to maintain higher activity at industrial process temperatures while extending its functional half-life, enabling faster processing without sacrificing enzyme durability.
3Reliability
If proteases are used for environmental degradation at low temperatures, then enzyme stability is improved, but degradation rate deteriorates
Solution Approach 1:
The amino acid modifications in the protease variants alter the temperature-activity profile of the enzyme. The modified proteases exhibit shifted parameters that allow them to maintain both stability and high degradation rates across a broader temperature range, including lower environmental temperatures, thus resolving the trade-off between stability and degradation rate.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The protease variants demonstrate enhanced thermostability and degrading activity, allowing efficient degradation of polylactic acid-containing materials under industrial conditions and environmental degradation scenarios, with improved residual activity and half-life compared to parent proteases.
Implementation Method 1
Proteases are able to catalyze the hydrolysis of a variety of polymers, including polyesters
Implementation Method 2
enzymes are able to accelerate hydrolysis of polyester containing material
Data Source
AI summary
The present invention relates to novel proteases, more particularly to protease variants having improved thermostability compared to the protease of SEQ ID N°1 and the uses thereof for degrading polyester containing material, such as plastic products. The proteases of the invention are particularly suited to degrade polylactic acid, and material containing polylactic acid.