Phi29 DNA Polymerase Mutants for Thermal Stability at 65°C
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Solution Overview
Problem
Phi29 DNA polymerase exhibits poor thermal stability, leading to inactivation at 65°C for 10 minutes, which affects storage life and DNA amplification efficiency, and existing mutations for improved stability can compromise other polymerase functions and increase patent infringement risks.
Innovation Solution
A phi29 DNA polymerase mutant with specific point mutations at positions 97, 123, and 515, such as M97A/L123H/E515P, maintains stability while preserving functional integrity and avoiding patent infringement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If phi29 DNA polymerase is heated at 65°C for 10 minutes, then thermal stability is improved, but the enzyme is inactivated and loses catalytic activity
Solution Approach 1:
The patent applies parameter changes by introducing specific point mutations (M97A/L123H/E515P) at amino acid positions 97, 123, and 515 of the phi29 DNA polymerase sequence. These mutations alter the physical and chemical parameters of the enzyme structure, specifically enhancing thermal stability while preserving catalytic activity. The mutations create new molecular interactions that stabilize the enzyme's three-dimensional structure at elevated temperatures without disrupting the active site functionality.
2Stability of the object's composition
If existing point mutations (M97T, L123S, E515A or E515R/K) are introduced to improve thermal stability, then thermostability increases, but other polymerase functions are affected
Solution Approach 1:
The patent applies local quality by making highly specific local changes at three predetermined amino acid positions (97, 123, and 515) rather than random or extensive mutations. Each mutation is strategically selected to affect only the thermal stability property while leaving other functional domains intact. The M97A, L123H, and E515P mutations are located in regions that influence structural stability without interfering with the catalytic core, strand displacement, or exonuclease activities.
3Duration of action of stationary object
If phi29 DNA polymerase product is stored, then storage life is extended, but thermal instability causes inactivation and reduces storage quality
Solution Approach 1:
The patent applies preliminary action by pre-modifying the phi29 DNA polymerase enzyme through specific point mutations (M97A/L123H/E515P) to enhance its thermal stability before storage. This preliminary structural modification ensures the enzyme maintains its catalytic activity and functional integrity during storage periods, preventing thermal inactivation that would otherwise occur with the wild-type enzyme. The mutated enzyme is prepared in advance with improved stability properties that persist throughout storage and subsequent use.
Data Source
AI summary
Provided are a group of phi29 DNA polymerase mutants having increased thermal stability and use thereof. The phi29 DNA polymerase mutants are proteins obtained by performing point mutation A and/or point mutation B and/or point mutation C on phi29 DNA polymerase, the point mutation A meaning that an amino acid residue M at position 97 of the phi29 DNA polymerase is mutated to other amino acid residue, the point mutation B meaning that an amino acid residue L at position 123 of the phi29 DNA polymerase is mutated into other amino acid residue, and the point mutation C meaning that an amino acid residue E at position 515 of the phi29 DNA polymerase is mutated to other amino acid residue. The stability of the phi29 DNA polymerase mutants is higher than that of a wild-type phi29 DNA polymerase.