Coupled Enzyme Screening for TDO and IDO Inhibitors
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Solution Overview
Problem
Current methods for screening tryptophan-2,3-dioxygenase (TDO) and indoleamine-2,3-dioxygenase (IDO) inhibitors are not suitable for high-throughput screening due to interference from background compounds, harsh conditions, and the need for intact cells or tissue homogenates, limiting the identification of effective inhibitors.
Innovation Solution
A high-throughput coupled enzyme method involving reacting tryptophan with isolated TDO or IDO in the presence of a test compound to form N-formylkynurenine, followed by conversion to kynurenine using kynurenine formamidase, with a reducing system that maintains enzyme activity without interfering with formamidase, allowing for detection of inhibitors through absorbance or fluorescence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current screening methods are used to detect TDO and IDO inhibitors, then inhibitor identification can be performed, but false positives occur due to background compound interference and the methods are not suitable for high-throughput screening
Solution Approach 1:
The patent extracts and measures the specific product N-formylkynurenine formed by TDO/IDO enzyme activity, separating it from background interference. By using a coupled enzyme system that converts N-formylkynurenine to kynurenine, the method isolates the signal of interest from interfering background compounds, enabling both high accuracy and high-throughput screening.
Solution Approach 2:
The patent introduces a coupled enzyme system with formamidase as an intermediary that converts N-formylkynurenine to kynurenine. This intermediary step amplifies the detectable signal and eliminates background interference, allowing accurate measurement of enzyme activity in high-throughput formats.
2Reliability
If harsh conditions are applied in screening methods, then enzyme activity can be maintained, but the methods require manual intervention and cannot be automated
Solution Approach 1:
The patent changes the reaction parameters to physiological conditions (pH 7.4, 37°C) that maintain enzyme activity without requiring harsh treatments. The coupled enzyme system with formamidase allows the reaction to proceed under mild, automated-compatible conditions while maintaining reliable enzyme activity measurement.
3Reliability
If intact cells or tissue homogenates are used, then enzyme activity can be preserved, but the complexity of the system prevents high-throughput screening
Solution Approach 1:
The patent segments the complex cellular system into isolated, purified enzymes (TDO or IDO) that can be handled individually in a controlled assay environment. This segmentation eliminates the complexity of intact cells or tissue homogenates while preserving enzyme activity, enabling straightforward high-throughput screening protocols.
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
This method reduces false positives, eliminates harsh conditions, and enables automation, significantly increasing sensitivity and scalability for identifying TDO and IDO inhibitors, facilitating the discovery of potential pharmaceutical candidates.
Implementation Method 1
Both enzymes catalyze the oxidative cleavage of the 2,3 double bond in the indole ring, converting tryptophan to N-formylkynurenine.
Implementation Method 2
reacting N-formylkynurenine from step (a) with isolated kynurenine formamidase to form kynurenine
Implementation Method 3
step (a) is conducted in the presence of a reducing system suitable for converting IDO and/or TDO from the Fe3+ to the Fe2+ state
Implementation Method 4
detecting the kynurenine produced in step (b) and determining whether the test compound is a TDO and/or an IDO inhibitor compound or not from the presence or absence or quantity of the detected kynurenine
Implementation Method 5
allowing for detection of inhibitors through absorbance or fluorescence
Data Source
AI summary
Provided is a high-throughput coupled enzyme method of screening for a tryptophan-2,3-dioxygenase (TDO) inhibitor compound and/or an indoleamine-2,3-dioxygenase (IDO) inhibitor compound, which method comprises: (a) reacting tryptophan with isolated IDO and/or isolated TDO in the presence of a test compound to form N-formylkynurenine; (b) reacting N-formylkynurenine from step (a) with isolated kynurenine formamidase to form kynurenine; and (c) detecting the kynurenine produced in step (b) and determining whether the test compound is a TDO and/or an IDO inhibitor compound or not from the presence or absence or quantity of the detected kynurenine, wherein step (a) is conducted in the presence of a reducing system suitable for converting IDO and/or TDO from the Fe3+ to the Fe2+ state, and which does not prevent the formation of kynurenine in step (c).