CTP Quantification via Cationic Ion Pairing Chromatography
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Solution Overview
Problem
Current methods for detecting and quantifying CTP and CTP synthase activity are time-consuming, costly, require high cell numbers, lead to protein denaturation, and lack specificity, making them unsuitable for routine hospital implementation and accurate CTP synthase activity determination.
Innovation Solution
Cationic ion pairing chromatography coupled with mass spectrometry, using a mobile phase with a pH between 6 and 7 and an acid sample pH, allows for rapid and specific detection and quantification of CTP and CTP synthase activity without protein denaturation, enabling efficient separation of CTP from other nucleotides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If radioisotope-based methods are used to detect and quantify CTP synthase activity, then measurement precision is improved, but loss of time and cost increase significantly
Solution Approach 1:
The patent extracts and eliminates the radioisotope labeling step from the detection process. Instead of using radiolabeled UTP, the method directly quantifies CTP and UTP levels using liquid chromatography coupled with tandem mass spectrometry, removing the time-consuming radioisotope incorporation and decay waiting periods while maintaining measurement precision through accurate mass spectrometric detection.
Solution Approach 2:
The patent replaces the radioisotope-based detection mechanism with mass spectrometry detection. The mechanical/chemical process of radioisotope labeling and radioactive counting is substituted with a mass-to-charge ratio-based detection system that provides equivalent or superior precision without the time delays associated with radioisotope methods.
2Measurement precision
If conventional chromatographic separation methods are used, then CTP and UTP can be separated, but separation time and total analysis duration increase beyond 15 minutes
Solution Approach 1:
The patent optimizes chromatographic parameters including mobile phase composition (acetonitrile-water gradients with formic acid), flow rates, column temperature, and gradient profiles to achieve rapid separation. These parameter changes enable complete separation of CTP and UTP within 15 minutes while maintaining the resolution needed for accurate quantification, thereby increasing analytical throughput.
3Ease of operation
If standard cell extract preparation methods are used, then sample preparation is simplified, but CTP synthase protein denaturation occurs preventing accurate activity measurement
Solution Approach 1:
The patent applies preliminary protective action by adding protease inhibitors and maintaining optimal pH conditions during sample collection and processing. The cell extracts are prepared and stabilized before any denaturation can occur, ensuring CTP synthase remains active throughout the assay process. This preliminary protection allows simple sample preparation to coexist with reliable enzyme activity measurement.
4Productivity
If tandem mass spectrometry is used without chromatographic separation, then analysis time is reduced, but measurement precision decreases due to 12% interference between UTP and CTP
Solution Approach 1:
The patent applies a partial separation approach using chromatography that provides just enough resolution to reduce the UTP-CTP interference to acceptable levels, rather than implementing complete or excessive separation. This partial chromatographic separation, combined with targeted mass spectrometry detection, achieves the optimal balance between maintaining measurement precision and preserving analysis speed, avoiding the need for lengthy separation 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 provides high specificity and accuracy in detecting and quantifying CTP and CTP synthase activity in a short time, using fewer cells and avoiding protein denaturation, making it suitable for routine hospital use and effective in screening immunosuppressive or anti-cancer compounds.
Implementation Method 1
separating the distinct triphosphate nucleotides by ion pairing chromatography using a cationic ion pair reagent contained in a mobile phase
Implementation Method 2
detecting or quantifying CTP by mass spectrometry
Data Source
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AI summary
The present invention relates to a method for detecting or quantifying CTP in a cell sample comprising at least two nucleotide triphosphates by cationic ion pairing chromatography coupled to mass spectrometry, to a method for detecting or quantifying CTP synthase activity based on the method for detecting or quantifying CTP, and to their use in methods for screening potential immunosuppressive or anti-cancer compounds and in methods for determining the appropriate dose of an immunosuppressive or anti-cancer compound inhibiting CTP synthase activity for a treated subject.