Nitrile Hydratase Mutant Thermal Stability
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Solution Overview
Problem
Current nitrile hydratase enzymes used in nicotinamide production suffer from low thermal stability and substrate/product tolerance, leading to reduced enzyme activity and increased energy consumption, which limits industrial production efficiency.
Innovation Solution
A genetically engineered nitrile hydratase mutant with specific amino acid mutations (αL6T/A19V/F126Y-βM46K/G47N/E108R/S212Y) is developed, enhancing thermal stability and substrate/product tolerance, and expressed in E. coli using the pET24a(+) vector for high-yield nicotinamide and acrylamide production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high temperature is used in the production process, then reaction rate increases, but enzyme activity decreases due to structural damage
Solution Approach 1:
The patent applies parameter changes by modifying the amino acid sequence of nitrile hydratase through site-directed mutagenesis. Specific mutations (αL6T/A19V/F126Y-βM46K/G47N/E108R/S212Y) are introduced to alter the enzyme's thermal stability parameters, allowing it to maintain activity at higher temperatures where wild-type enzymes would denature.
Solution Approach 2:
The patent applies local quality by making targeted amino acid substitutions at specific positions within the enzyme structure. These localized changes at positions 6, 19, 126 in the α-subunit and 46, 47, 108, 212 in the β-subunit selectively enhance thermal stability without compromising the overall catalytic function of the enzyme.
2Productivity
If high-concentration organic matter is used as substrate or product, then production efficiency increases, but enzyme activity decreases rapidly due to structural destruction
Solution Approach 1:
The patent applies parameter changes by modifying the enzyme's amino acid composition to alter its tolerance parameters toward organic substrates and products. The mutations enhance the enzyme's ability to withstand high concentrations of nitriles and amides without structural degradation, enabling operation at industrially relevant substrate concentrations.
Solution Approach 2:
The patent applies this principle by creating a robust enzyme variant that can withstand harsh conditions and maintain activity throughout the catalytic process. The mutant enzyme's enhanced stability allows it to function effectively as a disposable biocatalyst in industrial settings where extreme conditions are necessary for economic viability.
3Quantity of substance
If traditional Rhodococcus rhodochrous J1 is used for catalysis, then nicotinamide can be produced, but growth cycle is long (100 h) and production efficiency is low (162 g/(L·h))
Solution Approach 1:
The patent applies copying by transferring the improved nitrile hydratase gene from Pseudonocardia thermophila into E. coli BL21, creating a recombinant bacterial system that copies the desirable catalytic properties of the original organism while utilizing the faster growth characteristics of E. coli. This host transfer enables both high nicotinamide production and reduced cultivation time.
Solution Approach 2:
The patent applies universality by expressing multiple components (α-subunit, β-subunit, and regulatory protein PtNHase-p) from the Pseudonocardia nitrile hydratase system within a single E. coli host. This multi-functional approach allows the recombinant bacteria to achieve both efficient catalysis and rapid growth cycles.
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 mutant enzyme exhibits improved thermal stability and substrate/product tolerance, resulting in higher enzyme activity and increased production yields of nicotinamide and acrylamide, with residual activity increased by 43% at 50°C and improved tolerance to high substrate and product concentrations.
Implementation Method 1
Nitrile hydratase (NHase) can be used for catalysis of 3-cyanopyridine to nicotinamide
Implementation Method 2
catalysis of 3-cyanopyridine to nicotinamide
Implementation Method 3
improve the thermal stability and tolerance of the nitrile hydratase
Implementation Method 4
tolerance of the nitrile hydratase to substrates and products
Data Source
AI summary
The disclosure discloses a nitrile hydratase mutant, a genetically engineered bacterium containing the mutant and applications thereof, and belongs to the technical field of enzyme engineering. In the disclosure, glycine at position 47 of a nitrile hydratase mutant αL6T/A19V/F126Y-βM46K/E108R/S212Y (disclosed in the patent of disclosure CN102216455A) is mutated to asparagine. The obtained new mutant enzyme has better temperature tolerance and tolerance to a product, and is conducive to future industrial production. The recombinant strain containing the nitrile hydratase mutant is fermented at high density, and 3-cyanopyridine is used as a substrate to carry out a whole-cell catalytic reaction to prepare nicotinamide. Compared with a chemical production method, the method has a safe and clean production process and no environmental pollution. Compared with an enzymatic method, the substrate price is cheap and the catalytic efficiency is high. The yield of the final product nicotinamide is over 95%, the concentration reaches 680 g/L, and the separation and purification steps of the product are simplified.