Transaminase Mutant Engineering for High-EE Sitagliptin Intermediates
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Solution Overview
Problem
Existing transaminases exhibit poor stereoselectivity and limited substrate spectrum, leading to low yields and high costs in the synthesis of sitagliptin intermediates, with existing biocatalysts being unsuitable for direct use with sitagliptin precursor ketones.
Innovation Solution
A transaminase mutant derived from Mycolicibacterium, engineered with specific amino acid substitutions, is used in a biocatalytic reaction system with sitagliptin precursor ketones and esters, along with pyridoxal phosphate and isopropyl amine, to achieve high stereoselectivity and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing transaminases are used for synthesis of sitagliptin intermediates, then the reaction can proceed, but the stereoselectivity is poor and yield is low
Solution Approach 1:
The patent applies parameter changes by modifying the amino acid sequence of the transaminase enzyme through directed evolution. Specific mutations were introduced at positions 74, 228, 254, and 290 to optimize the enzyme's catalytic properties. This resulted in a mutant transaminase with enhanced stereoselectivity achieving >99% ee value and improved yield reaching 82% total yield, directly resolving the contradiction between manufacturing precision and productivity.
Solution Approach 2:
The patent employs feedback mechanisms through iterative screening and selection processes. The enzyme library was generated through mutagenesis, and mutants were screened for their catalytic performance in sitagliptin intermediate synthesis. The feedback from screening results guided further mutagenesis cycles, progressively improving both stereoselectivity and yield until the optimal mutant was obtained.
2Adaptability or versatility
If existing transaminases with narrow substrate spectrum are used, then specific reactions can be catalyzed, but the application scope is limited
Solution Approach 1:
The patent achieves universality by engineering a broad-spectrum transaminase mutant capable of catalyzing multiple substrates related to sitagliptin synthesis. The mutant enzyme demonstrated versatility in accepting different substrate variants while maintaining high catalytic efficiency and stereoselectivity, expanding the application scope from single-specific reactions to multi-substrate catalysis.
Solution Approach 2:
Through systematic mutagenesis and directed evolution, the patent modified the enzyme's active site and structural parameters to enhance substrate binding flexibility. These parameter changes enabled the transaminase to accommodate a broader range of substrates while preserving high catalytic efficiency, resolving the contradiction between adaptability and reliability.
3Ease of manufacture
If conventional biocatalysts are used for sitagliptin intermediate synthesis, then the process can be carried out, but the catalyst cost is high and solvent recovery is difficult
Solution Approach 1:
The patent employs a disposable enzyme catalyst approach where the engineered transaminase mutant is used in a stable, cost-effective manner. The mutant enzyme demonstrates enhanced stability and reusability, reducing the need for expensive catalyst recovery processes. The simplified purification and recovery procedures lowered production costs while maintaining high raw material conversion rates, resolving the contradiction between ease of manufacture and 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 method achieves a total yield of 82% and an e.e. value of 99% for sitagliptin intermediates, overcoming the limitations of existing methods by using a broad-spectrum transaminase mutant.
Implementation Method 1
The key to the chemo-enzymatic method is to obtain a transaminase that can catalyze asymmetric transamination reaction to obtain optically pure sitagliptin intermediates
Implementation Method 2
pyridoxal phosphate as a coenzyme
Data Source
Figure 1
AI summary
The present invention discloses a transaminase mutant and application thereof in preparation of sitagliptin intermediates, the transaminase mutant is obtained by substitution of tyrosine with proline at position 74, substitution of glutamic acid with aspartic acid at position 228, substitution of leucine with alanine at position 254 and substitution of methionine with threonine at position 290 of the amino acid sequence shown in SEQ ID NO: 2. The present invention uses wet cells or a purified transaminase as a biocatalyst and a sitagliptin precursor ketone or a prochiral carbonyl compound as a substrate to prepare a sitagliptin intermediate or a sitagliptin ester intermediate; the total yield of the method reaches about 82%, and e.e. value of the product reaches 99%.