A multiple mass spectral line method for determining positional specific activities in stable isotope-labeled amino...

Area of Science:

• Analytical Chemistry
• Biochemistry
• Isotope Chemistry

Background:

• Isotopically labeled amino acids are vital tracers in biological research.
• Accurate determination of label position and enrichment is essential for quantitative analysis.

Purpose of the Study:

• To develop and validate a gas chromatography/mass spectrometry (GC/MS) method for precise isotope label positioning and enrichment determination in amino acids.
• To investigate the utility of the method for various amino acids and labeling patterns.

Main Methods:

• Preparation and analysis of standards for specific isotope-labeled amino acids (lysine, alanine, leucine, aspartic acid).
• Utilized gas chromatography/mass spectrometry under both scan and selective ion monitoring (SIM) conditions.
• Identified characteristic mass spectrometry line pairs for different isotope labels and positions.

Main Results:

• Successfully identified characteristic line pairs for various isotope labels ([15N], [13C]) and positions within amino acids.
• Verified the method's precision and accuracy through analysis of mixtures containing different labels or positional isomers.
• Achieved high precision in enrichment determination with relative errors ranging from 0.14% to 36%.

Conclusions:

• The developed GC/MS method provides a precise and reliable approach for determining isotope label position and enrichment in amino acids.
• This technique is applicable to a range of amino acids and labeling strategies, supporting advanced metabolic and proteomic studies.