A comparison of derivatives of alanine and d-alanine used in gas chromatography-mass spectrometry analysis for protein kinetics

Authors: KAUFMANN, YIHONG - Arkansas Children'S Nutrition Research Center (ACNC); WILLIAMS, RICK - University Arkansas For Medical Sciences (UAMS); COTTER, MATTHEW - Arkansas Children'S Nutrition Research Center (ACNC); FERRANDO, ARNY - University Arkansas For Medical Sciences (UAMS); BØRSHEIM, ELISABET - Arkansas Children'S Nutrition Research Center (ACNC)

Submitted to: Journal of Proteome Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2025
Publication Date: 3/16/2025
Citation: Kaufmann, Y., Williams, R., Cotter, M., Ferrando, A., Børsheim, E. 2025. A comparison of derivatives of alanine and d-alanine used in gas chromatography-mass spectrometry analysis for protein kinetics. Journal of Proteome Research. 24(4). https://doi.org/10.1021/acs.jproteome.4c01004.
DOI: https://doi.org/10.1021/acs.jproteome.4c01004

Interpretive Summary: Problem: Scientists use heavy water, which contains a heavier form of hydrogen called deuterium, to study how the body processes nutrients. One challenge in this research is accurately measuring an amino acid called alanine after it interacts with heavy water in the body. To do this, scientists must modify alanine using special chemicals before it is measured on special equipment, but the best chemical for this process had not been clearly identified. Some chemicals might be less reliable or even damage the lab equipment, making research more difficult. Accomplishment: Scientists in Little Rock, AR, tested two different chemicals, Methyl-8 and MtBSTFA, to determine which one was the most accurate, sensitive, and reliable for measuring alanine. They also evaluated how each chemical affected the lab equipment. The results showed that while both chemicals could be used, MtBSTFA was the better choice because it performed more consistently and did not damage the equipment like Methyl-8 did. Contribution of Accomplishment to Solving the Problem: By identifying MtBSTFA as the best chemical for this process, the research improves the accuracy and reliability of studies using heavy water. This helps scientists better understand how the body processes nutrients, leading to advancements in health research and metabolic studies.

Technical Abstract: Stable isotope techniques serve as invaluable tools for kinetic measurements in metabolic research. In particular, deuterated water (D2O) administration is increasingly applied in human health research. For use in protein kinetic studies, this includes measurements on gas chromatography-mass spectrometer of alanine (ALA) and deuterium-labelled alanines (d-ALAs) coming from D2O administration. However, the choice of derivative of ALA and d-ALAs used in such analyses has not been evaluated thoroughly. Hence, we conducted a comprehensive head-to-head comparison to determine the most effective and reliable derivative. Two derivatization reagents, N,N-dimethylformamide dimethyl acetal (methyl-8 reagent) and N-Methyl-N-tert-butyldimethylsilyltrifluoroacetamide (MtBSTFA) were considered as candidates. Using chemical standards and available rodent muscle tissue, both reagents underwent testing, including standard curve linear regression fit, sensitivity, reproducibility, and, importantly, column effectiveness. Our findings indicate that both reagents were suitable for ALA/d-ALAs analyses. However, MtBSTFA derivative exhibited better linear regression fit, higher sensitivity, and greater reproducibility than methyl-8. More importantly, the methyl-8 derivative resulted in severe column damage. In conclusion, our study highlights the MtBSTFA derivative as a preferred choice for ALA and d-ALAs gas chromatography-mass spectrometry (GC-MS) analysis, contributing to a reliable and sensitive analytical method for D2O administration studies for measurements of in vivo metabolic rates.