Title: USE OF A 13C TRACER TO INVESTIGATE LUTEIN AS A LIGAND FOR PLASMA TRANSTHYRETIN IN HUMANS
White, Wendy - IOWA STATE UNIVERSITY
Chen, Liwei - IOWA STATE UNIVERSITY
Collins, Xixuan - IOWA STATE UNIVERSITY
Submitted to: Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: December 1, 2004
Publication Date: April 5, 2005
Citation: White, W.S., Chen, L., Collins, X.H., Tabatabai, L.B. 2005. Use of a 13c tracer to investigate lutein as a ligand for plasma transthyretin in humans. Experimental Biology. Abstract #291.12.
Lutein is detected in association with serum transthyretin (TTR) in chickens but not in humans. However, chickens are fed rations supplemented with lutein as a source of broiler and yolk pigmentation. Our objective was to use a uniformly-labeled 13C-lutein tracer and gas chromatograph combustion interfaced isotope ratio mass spectrometry (GC C IRMS) as a high-sensitivity approach to investigate lutein as a physiological ligand for plasma TTR in humans. Subjects (n = 4) each ingested 1 mg 13Clutein daily for 3 days and donated blood 24 hours after the final dose. The plasma TTR retinol-binding protein (RBP) complex was partially purified by anion-exchange (DEAE)chromatography and dissociated by hydrophobicinteraction chromatography. The crude transthyretin fractions were then purified to homogeneity by RBP Sepharose affinity chromatography. Pure TTR was extracted with chloroform and unlabeled lutein was added to the extract as a carrier. The mean 13C/12C ratio (expressed in delta notation, '13C) of the lutein fractions isolated from the plasma TTR extracts of the subjects was -30.53 ± 3.29. The 13C value of the unlabeled lutein carrier was -30.97 ± 0.27. Thus no 13C enrichment was detected in association with TTR. We conclude that lutein is not associated with TTR in human plasma after lutein is ingested in physiological amounts. Supported by Kemin Foods, LC.