NADH-Specific Oxidoreductase for Stereoselective Keto Reduction
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Solution Overview
Problem
Current enzymatic processes for stereoselective reduction of keto compounds face limitations due to the availability of robust, NADH-dependent, R-specific oxidoreductases that can perform substrate-coupled coenzyme regeneration, particularly with high stability towards secondary alcohols like isopropanol and ease of expression in E. coli, which are essential for industrial applications.
Innovation Solution
Identification and characterization of stable, NADH-dependent, R-specific oxidoreductases with specific amino acid sequences and features, such as an N-terminal Rossmann fold and catalytic triad, that are suitable for industrial use and can regenerate cofactors using secondary alcohols, expanding the portfolio of industrially accessible enzymes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chemical asymmetric hydrogenation is used for reduction of keto compounds, then the reaction can proceed under standard conditions, but highly toxic heavy metal catalysts and large amounts of organic solvents are required
Solution Approach 1:
The patent replaces chemical catalysis with enzymatic catalysis, substituting heavy metal catalysts with biocatalysts (oxidoreductases). This substitution eliminates the need for toxic heavy metals while maintaining catalytic functionality, directly resolving the contradiction between reaction efficiency and environmental harm
Solution Approach 2:
The patent changes the reaction conditions from requiring large amounts of organic solvents to using aqueous buffers with minimal or no organic solvents. This parameter change reduces environmental harm while maintaining productively through the enzymatic catalysis mechanism
2Productivity
If chemical asymmetric hydrogenation is used, then reduction can be achieved, but extreme and energy-intensive reaction conditions are required
Solution Approach 1:
The patent substitutes chemical hydrogenation requiring extreme conditions with enzymatic reduction that proceeds under mild physiological conditions. The enzyme catalysts enable the reaction to occur at ambient temperature and pressure, dramatically reducing energy consumption while maintaining productivity
3Productivity
If chemical asymmetric hydrogenation is used, then reduction can proceed, but side reactions occur and enantiomeric excesses are insufficient
Solution Approach 1:
The patent employs enzymes with highly specific active sites that are tailored to recognize and catalyze the reduction of specific keto substrates with high stereoselectivity. This local specificity at the molecular level ensures high enantiomeric excess and prevents side reactions, resolving the contradiction between productivity and manufacturing precision
4Manufacturing precision
If NADPH-dependent oxidoreductases are used for reduction, then enantioselective reduction can be achieved, but process costs increase due to expensive NADPH cofactor
Solution Approach 1:
The patent implements an in situ cofactor regeneration system where NAD+ is reduced back to NADH by a secondary alcohol dehydrogenase using inexpensive secondary alcohols as substrates. This recycling approach eliminates the need for continuous addition of expensive NADPH, maintaining enantioselectivity while dramatically reducing process costs
5Productivity
If oxidoreductases are used in aqueous/organic two-phase systems, then efficiency and economy improve, but the system complexity increases
Solution Approach 1:
The patent employs enzymes that function effectively in simplified aqueous buffer systems without requiring complex two-phase setups. The enzymatic system maintains high efficiency in simple aqueous environments, eliminating the need for organic phases and reducing system complexity while preserving productivity
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 identified oxidoreductases demonstrate high stability and activity in reducing keto compounds with high enantiomeric purity and yield, enabling broad substrate coverage and efficient enzymatic reduction processes under process engineering conditions.
Implementation Method 1
The asymmetric reduction of prochiral keto compounds is a sector of stereoselective catalysis in which biocatalysis represents a powerful competing technology to chemical catalysis
Implementation Method 2
Reductions of prochiral keto compounds to hydroxy compounds and reverse oxidations occur in nature in numerous biochemical pathways
Implementation Method 3
Coenzyme regeneration is achieved through the simultaneous oxidation of secondary alcohols
Data Source
AI summary
The invention relates to a method for stereoselectively, in particular enantioselectively, and enzymatically reducing keto compounds to the corresponding chiral hydroxy compounds, wherein the keto compounds are reduced using an enantioselective, NADH-specific oxidoreductase, wherein in order to reduce the keto compounds, a polypeptide is used that has an R-ADH signature H-[P; A]-[I; A; Q; V; L]-[G; K]-R at position 204-208 and the following further structural characteristics in the entirety thereof: (i) an N-terminal Rossmann fold GxxxGxG, (ii) a NAG motif at position 87, (iii) a catalytic triad comprising S 139, Y 152, and K 156, (iv) a negatively charged amino acid group at position 37, (v) two C-terminal motifs in the dimerization domain [A; S]-S-F and [V; I]-DG-[G; A]-Y-[T; C; L]-[A; T; S]-[Q; V; R; L; P], (vi) VaI or Leu at position 159 (4 places down from K 156), (vii) Asn at position 178, and (viii) a proline group at position 188.