Determination of muscle protein synthesis rates in fish using 2H2O and 2H NMR analysis of alanine

Following administration of deuterated water (2H2O), the fractional synthetic rate (FSR) of a given endogenous protein can be estimated by 2H-enrichment quantification of its alanine residues. Currently, this is measured by mass spectrometry following a derivatization procedure. Muscle FSR was measured by 1H/2H NMR analysis of alanine from seabass kept for 6 days in 5% 2H-enriched saltwater, following acid hydrolysis and amino acid isolation by cation-exchange chromatography of muscle tissue. The analysis is simple and robust, and provides precise measurements of excess alanine 2H-enrichment in the 0.1–0.4% range from 50 mmol of alanine recovered from muscle protein.