Alpha-L-iduronidase Assay via Tandem Mass Spectrometry

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Solution Overview

Problem

Current newborn screening methods are inadequate for early detection of Mucopolysaccharidosis Type I (MPS-I), a lysosomal storage disorder caused by α-L-iduronidase deficiency, which requires early intervention for effective treatment.

Innovation Solution

A method for assaying α-L-iduronidase enzymatic activity using a substrate and internal standard, involving incubation, quenching, extraction with an organic solvent, and tandem mass spectrometric analysis to determine the enzyme product's quantity, facilitating early detection of MPS-I in newborns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If fluorometric or radiometric assays are used for α-L-iduronidase measurement, then sensitivity is improved, but device complexity and cost increase

Engineering Contradiction:

Improveenzyme activity detection sensitivityVSAvoidassay system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex fluorometric or radiometric detection systems with tandem mass spectrometry, which provides comparable sensitivity for enzyme activity measurement while simplifying the overall assay system and reducing costs associated with specialized optics or radioisotopes

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the detection parameter from fluorescence intensity or radioactivity to mass-to-charge ratio, enabling enzyme product quantification through mass spectrometry which offers high sensitivity without requiring complex optical or radiological equipment

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If tandem mass spectrometry is used for enzyme activity measurement, then measurement precision is improved, but productivity decreases due to extended analysis time

Engineering Contradiction:

Improveenzyme product quantification accuracyVSAvoidscreening throughput

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent performs preliminary extraction of the enzyme product from the reaction mixture before mass spectrometry analysis, using organic solvent extraction to concentrate the analyte and remove interfering substances, which reduces analysis time and improves throughput while maintaining high measurement precision

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention extracts the enzyme product from the complex biological matrix using organic solvent, isolating the target analyte before analysis. This extraction step eliminates the need for extensive sample preparation during the actual measurement, thereby improving productivity without sacrificing precision

Inventive Principle:

Principle #2Taking out (Extraction)

3Loss of time

If early detection methods are developed for MPS-I, then loss of time for treatment initiation is reduced, but device complexity increases

Engineering Contradiction:

Improvetime to diagnosisVSAvoidscreening method complexity

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The patent employs an internal standard that automatically compensates for variations in sample preparation and instrument performance, eliminating the need for complex calibration procedures or quality control protocols, thus enabling rapid screening without increasing device complexity

Inventive Principle:

Principle #25Self-service

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

Enables accurate and efficient screening for α-L-iduronidase activity in newborns, distinguishing between affected, carrier, and unaffected individuals, thereby identifying candidates for MPS-I treatment.

Implementation Method 1

extracting an aqueous enzyme reaction mixture comprising an α-L-iduronidase, an α-L-iduronidase product, and an α-L-iduronidase internal standard with an organic solvent to provide an organic phase comprising the α-L-iduronidase product and α-L-iduronidase internal standard

Methodology Applied

Scientific EffectLiquid-liquid extraction: Liquid-Liquid Extraction