Mutant Protease Acidic Stability via Position 303 Substitution
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Solution Overview
Problem
Existing liquid detergents face challenges in stabilizing proteases at acidic pH due to the presence of surfactants and other components, which affects their washing performance.
Innovation Solution
A mutant protease with an amino acid sequence having at least 90% identity to a specific sequence (SEQ ID NO:2) is developed, where the amino acid residue at position 303 is substituted with specific amino acids to enhance stability under acidic conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protease with alkaline optimum pH is used in liquid detergent, then washing performance on composite stains is improved, but stability in acidic liquid detergent is worsened
Solution Approach 1:
The invention changes the pH stability parameter of the protease by introducing specific amino acid substitutions (G303D, G303E, G303F, G303H, G303I, G303M, G303N, G303P, G303Q, G303T, G303V, G303W, or G303Y). These substitutions modify the enzyme's structural properties to expand its pH stability range from alkaline only to both acidic and alkaline conditions, while maintaining high protease activity across a broader pH spectrum including pH 3-11.
2Adaptability or versatility
If liquid detergent contains surfactants and other components, then various detergent functions are achieved, but enzyme preservation stability is worsened
Solution Approach 1:
The invention modifies the protease's structural parameters through amino acid substitutions at position 303, enhancing its resistance to denaturation by surfactants and other detergent components. The mutant proteases demonstrate improved stability in the presence of cationic surfactants and other liquid detergent ingredients, maintaining enzymatic activity where wild-type proteases would be inactivated.
3Object-generated harmful factors
If pH of liquid detergent is made weakly acidic or strongly acidic to reduce smell, then antibacterial property is improved, but protease stability is worsened
Solution Approach 1:
The invention expands the pH stability window of the protease through specific amino acid substitutions, enabling the enzyme to remain stable and active in weakly acidic to strongly acidic conditions (pH 3-6). This allows liquid detergents to be formulated at acidic pH levels for smell reduction and enhanced antibacterial properties while maintaining effective protease activity for stain removal.
Data Source
AI summary
Provided is a mutant protease with improved stability under acidic condition. A mutant protease that consists of the amino acid sequence as shown in SEQ ID NO:2 or an amino acid sequence having an identity of at least 90% thereto, in which the amino acid residue at a position corresponding to position 303 in the amino acid sequence as shown in SEQ ID NO:2 is substituted with another amino acid residue.