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Updated: May 21, 2026
Natural Product Discovery with LC-MS/MS Diagnostic Fragmentation Filtering: Application for Microcystin Analysis
Published on: May 31, 2019
Highly sensitive detection and discrimination of LR and YR microcystins based on protein phosphatases and an
O I Covaci1, A Sassolas, G A Alonso
1Laboratoire IMAGES EA 4218, University of Perpignan Via Domitia, Perpignan, France.
Abstract:
The inhibition characteristics of three different protein phosphatases by three microcystin (MC) variants--LR, YR, and RR--were studied. The corresponding K (I) for each enzyme-MC couple was calculated. The toxicity of MC varies in the following order: MC-LR > MC-YR > MC-RR. The sensitivity of the enzymes increased in the following order: mutant PP2A < mutant PP1 < natural PP2A. The best limit of detection obtained was 21.2 pM MC-LR using the most sensible enzyme. Methanol, ethanol, and acetonitrile up to 2 % (v/v) may be used in inhibition measurements. An artificial neural network (ANN) was used to discriminate two MC variants--LR and YR--using the differences in inhibition percentages measured with mutant PP1 and natural PP2A. The ANN is able to analyze mixtures with concentrations ranging from 8 to 98 pM MC-LR and 31 to 373 pM MC-YR.
Insights
This study investigated microcystin (MC) variants and their inhibition of protein phosphatases, finding MC-LR is most toxic. An artificial neural network effectively detected MC mixtures.
Area of Science:
- Environmental toxicology
- Biochemistry
- Analytical chemistry
Background:
- Microcystins (MCs) are potent cyanotoxins with varying toxicity.
- Protein phosphatases are key cellular targets for MCs.
- Accurate detection and discrimination of MC variants are crucial for risk assessment.
Purpose of the Study:
- To characterize the inhibition of protein phosphatases by different MC variants (MC-LR, MC-YR, MC-RR).
- To determine the sensitivity of various protein phosphatases to MCs.
- To develop an analytical method for detecting and quantifying MC mixtures.
Main Methods:
- Enzyme inhibition assays were performed using three protein phosphatase variants (natural PP2A, mutant PP1, mutant PP2A) and three MC variants.
- Inhibition constants (K_I) were calculated for each enzyme-MC pair.
- An artificial neural network (ANN) was employed to analyze inhibition data for MC discrimination and quantification.
Main Results:
- Toxicity order was determined as MC-LR > MC-YR > MC-RR.
- Enzyme sensitivity varied: mutant PP2A < mutant PP1 < natural PP2A.
- A detection limit of 21.2 pM for MC-LR was achieved.
- The ANN successfully discriminated MC-LR and MC-YR and quantified mixtures within specific concentration ranges.
Conclusions:
- MC-LR exhibits the highest toxicity and inhibition potency.
- Specific protein phosphatase variants show differential sensitivity to MCs.
- ANN provides a robust method for sensitive MC detection and mixture analysis.
