Analysis of (1-13C)leucine and (13C)KIC in plasma by capillary gas chromatography/mass spectrometry in protein turnover studies.
The methods used for the determination of the concentration and isotope enrichment of (1-13C)leucine and its metabolite (13C) alpha-ketoisocaproic acid (KIC) in plasma for the study of whole-body protein turnover are described. Leucine was analysed as its N-heptafluorobutyryl isobutyl ester and KIC as its quinoxalinol-TMS derivative, both by chemical ionization selected ion monitoring gas chromatography/mass spectrometry (GC/MS). The sensitivity of the leucine assay was improved 30 times by monitoring the negative ions under the conditions described. The coefficient of variation for enrichment and concentration measurements were 0.5% and 2%, respectively, with a minimum detectable enrichment of 0.1 at% excess for both assays.
Ford
G C
GC
Cheng
K N
KN
Halliday
D
D
D002208:Caproates / Q000097:blood*; D002247:Carbon Isotopes; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006801:Humans; D007651:Keto Acids / Q000097:blood*; D007930:Leucine / Q000097:blood*; D011506:Proteins / Q000378:metabolism*
D002208:Caproates; D002247:Carbon Isotopes; D007651:Keto Acids; D011506:Proteins; C013082:alpha-ketoisocaproic acid; D007930:Leucine