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Metabolic Pathway Confirmation and Discovery Through 13C-labeling of Proteinogenic Amino Acids
Published on: January 26, 2012
Free amino acid quantification by LC-MS/MS using derivatization generated isotope-labelled standards
1SA Pathology, Dept of Genetic Medicine, Women's and Children's Hospital, 72 King William Road, North Adelaide, South Australia 5006, Australia. david.johnson@adelaide.edu.au
Summary
New derivatizing reagents significantly enhance plasma amino acid quantification using tandem mass spectrometry (MS/MS). These improved reagents offer greater sensitivity and specificity, potentially replacing traditional amino acid analyzers.
Area of Science:
- Analytical Chemistry
- Biochemistry
- Mass Spectrometry
Background:
- Plasma amino acid quantification is crucial for diagnosing metabolic disorders.
- Current methods like amino acid analyzers have limitations in sensitivity and specificity.
- Tandem mass spectrometry (MS/MS) offers high sensitivity but requires optimized derivatization reagents.
Purpose of the Study:
- To develop novel derivatizing reagents for improved plasma amino acid quantification by MS/MS.
- To enhance MS/MS product ion intensity and analytical specificity.
- To evaluate isotope-labeled standards for accurate quantification.
Main Methods:
- Systematic modification of the succinimide ester of 4-methylpiperazineacetic acid (MPAS).
- Synthesis and evaluation of 4-methylpiperazinebutyryl succinimide (MPBS) and dimethylaminobutyryl succinimide (DMABS).
- Preparation and use of deuterated analogues (d3-DMABS) as isotope-labeled standards.
Main Results:
- MPBS and DMABS yielded 10-100 fold greater MS/MS product ion signal intensity compared to MPAS.
- d3-DMABS provided acceptable accuracy and precision for amino acid quantification.
- DMABS derivatives enabled differentiation of structural isomers (e.g., valine/norvaline).
Conclusions:
- Novel DMABS and MPBS reagents significantly improve MS/MS sensitivity and specificity for amino acid analysis.
- Derivatization with isotope-labeled standards offers a viable alternative to conventional amino acid analyzers.
- This advancement facilitates more accurate and sensitive plasma amino acid quantification.
