Thermophilic Recombinant Type II Pullulanase for Starch Hydrolysis
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Solution Overview
Problem
Current thermophilic type II pullulanases have low catalytic efficiency and poor thermal stability, which limits their effectiveness in industrial starch processing and syrup production.
Innovation Solution
A recombinant Escherichia coli expressing a thermophilic type II pullulanase with enhanced protein secretion capacity under strong reductant conditions, using a pET series vector and optimizing the enzyme for high temperature and pH stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If currently reported type II pullulanase is used, then the enzyme can perform starch hydrolysis, but the catalytic efficiency is low and thermal stability is poor
Solution Approach 1:
The patent applies parameter changes by optimizing the amino acid sequence of type II pullulanase through site-directed mutagenesis. Specific amino acid residues were modified to enhance both thermal stability and catalytic efficiency simultaneously, transforming the enzyme's physical and chemical properties to achieve superior performance in starch hydrolysis applications
2Productivity
If traditional two-step amylase process is used, then starch liquefaction and saccharification can be performed, but the overall reaction time is too long and multiple parameter adjustments are required
Solution Approach 1:
The patent merges the functions of α-amylase and type II pullulanase into a single enzymatic system. The engineered pullulanase exhibits dual activity, performing both liquefaction and saccharification functions that traditionally required separate enzymatic steps, thereby simplifying the process and reducing overall reaction time
Solution Approach 2:
The engineered type II pullulanase achieves multi-functionality by simultaneously performing starch liquefaction and saccharification. This single enzyme replaces the need for multiple specialized enzymes, making the process more efficient and easier to control while maintaining product quality
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 recombinant type II pullulanase exhibits significantly higher specific enzyme activity and thermal stability, maintaining over 50% activity after 10 hours at 95°C, and its activity is enhanced by more than 40% under strong reducing conditions.
Implementation Method 1
Pullulanase (EC 3.2.1.41) is a starch debranching enzyme that can hydrolyze α-1,6-glycosidic linkage in amylopectin, pullulan, and the α-limit dextrin and β-limit dextrin
Implementation Method 2
The E. coli has an enhanced protein secretion capacity in a culture environment containing strong reductants
Data Source
AI summary
The present disclosure discloses a thermophilic recombinant type II pullulanase and the application thereof, and belongs to the technical field of genetic engineering. The present disclosure obtains a thermophilic recombinant type II pullulanase by heterologously expressing type II pullulanase in Escherichia coli. Its optimum pH is 6.6, it has better pH tolerance under the conditions of pH 5.8-8.0, and its optimum temperature is 95° C. After incubating at 95° C. for 10 h, the remaining enzyme activity is greater than 50%. It can exhibit higher specific enzyme activity under strong reducing conditions. For example, adding DTT to the culture environment can increase the specific enzyme activity of Sumo-PulPy by 237.2%. The present disclosure also provides the combined truncation mutant Δ28N+Δ791C of type II pullulanase Sumo-PulPy. The specific enzyme activity of the enzyme mutant is 32.18±0.92 U/mg, which is 5.99 times as high as that of the wild-type enzyme, thereby having important industrial application value and potential.