Abstract
We describe a method to measure protein synthesis and catabolism in humans without prior purification and use the method to measure the turnover of surfactant protein-B (SP-B). SP-B, a lung-specific, hydrophobic protein essential for fetal-neonatal respiratory transition, is present in only picomolar quantities in tracheal aspirate samples and difficult to isolate for dynamic turnover studies using traditional in vivo tracer techniques. Using infusion of [5,5,5-2H3] leucine and a targeted proteomics method, we measured both the quantity and kinetics of SP-B tryptic peptides in tracheal aspirate samples of symptomatic newborn infants. The fractional synthetic rate (FSR) of SP-B measured using the most abundant proteolytic fragment, a 10 amino acid peptide from the carboxy-terminus of proSP-B (SPTGEWLPR), from the circulating leucine pool was 0.035 ± 0.005 h- 1, and the fractional catabolic rate was 0.044 ± 0.003 h -1. This technique permits high-throughput and sensitive measurement of turnover of low abundance proteins with minimal sample preparation.
Original language | English |
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Pages (from-to) | 2561-2567 |
Number of pages | 7 |
Journal | Analytical Chemistry |
Volume | 82 |
Issue number | 6 |
DOIs | |
State | Published - Mar 15 2010 |