Alpha-Amylase Variants for Glucose Stability and Long-Chain Activity
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Solution Overview
Problem
Current alpha-amylases face stability issues at low sodium ion concentrations, low pH, and high temperatures, particularly at low calcium concentrations, which affects their performance in starch processing and ethanol production.
Innovation Solution
Development of alpha-amylase variants with specific substitutions, such as K176L+E185P+I201Y+H205Y+K213T+Q360S+D416V+R437W, that provide improved stability in the presence of glucose and increased activity on long chain substrates, enhancing their performance in challenging conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional alpha-amylases are used, then basic starch processing function is provided, but stability is poor at low pH, high temperature, and low calcium concentrations
Solution Approach 1:
The patent applies parameter changes by modifying specific amino acid residues at positions 176, 185, 201, 205, 213, 360, 416, and 437 of the alpha-amylase sequence. These positional parameters were systematically altered to enhance enzyme stability under challenging conditions including low pH, high temperature, and low calcium concentrations, while maintaining catalytic functionality.
Solution Approach 2:
The patent creates composite enzyme variants by combining multiple amino acid substitutions in specific patterns (Pattern A, Pattern B, Pattern C, or Pattern D). Each pattern represents a composite configuration of mutations that work synergistically to improve stability across multiple stress conditions simultaneously, rather than addressing each condition with separate enzyme variants.
2Reliability
If protein engineered variants are developed to improve stability, then stability at low pH and high temperature is improved, but complexity of enzyme design increases
Solution Approach 1:
The patent segments the enzyme design problem into four distinct substitution patterns (A, B, C, D), each targeting specific amino acid positions. This segmentation allows researchers to select appropriate patterns based on desired properties, reducing the complexity of designing stable variants by providing modular, pre-optimized substitution schemes rather than requiring de novo design of all possible mutations.
Solution Approach 2:
The patent applies local quality by focusing mutations on specific critical regions of the alpha-amylase molecule (positions 176, 185, 201, 205, 213, 360, 416, and 437). Rather than random mutagenesis throughout the entire sequence, the invention identifies and modifies only the local regions that most significantly impact stability under challenging conditions, simplifying the overall design process.
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 variants exhibit enhanced stability and activity on long chain substrates compared to parent alpha-amylases, improving process efficiency in starch processing and ethanol production, especially at low sodium ion concentrations and high temperatures.
Implementation Method 1
Alpha-amylases (E.C. 3.2.1.1) constitute a group of enzymes which catalyze hydrolysis of starch, glycogen and related polysaccharides and oligosaccharides
Data Source
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AI summary
The present invention relates to alpha-amylase variants with improved stability in the presence of glucose and/or relatively higher activity on long chain versus short chain substrates. The present invention also relates to polynucleotides encoding the variants; nucleic acid constructs, vectors, and host cells comprising the polynucleotides; and methods of using the variants.