Mass Spectrometric Methods for Determination of [13C]Leucine Enrichment in Human Muscle Protein

✍ Scribed by P. Balagopal; G.Charles Ford; David B. Ebenstein; Daniel A. Nadeau; K.Sreekumaran Nair

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 122 KB
• Volume: 239
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1006/abio.1996.0293

✦ Synopsis

synthesis rates of tissue proteins requires the measure-Two modified GC-based isotope ratio MS (IRMS) ment of isotopic enrichment in both the precursor pool techniques, for measurement of [ 13 C]leucine enrichand the tissue. When 13 C labels are used, the precursor ment in muscle protein, were compared with a convenpool enrichments with relatively high values (ú1 at.% tional dual inlet technique. Of these three, two inexcess) are routinely measured by gas chromatogravolved HPLC purification of leucine and liberation of phy/mass spectrometry (GC/MS). However, for 13 C carbon dioxide (CO 2 ) using the ninhydrin reaction. In analysis these instruments exhibit relatively low precithe conventional technique the CO 2 was introduced sion (0.1-0.5 mol% excess). Isotope ratio mass specinto the MS by a dual inlet system following cryogenic trometers (IRMS), 2 with greater precision (õ0.0001 concentration. In the second method (ninhydrin/GC/ at.% excess), are generally used to measure the low IRMS) the CO 2 was purified by on-line GC. In the third enrichments (0.001-0.05 at.% enrichment) found in technique, GC/combustion/IRMS, derivatized amino tissue proteins (1).