Blood glutathione synthesis rates in healthy adults receiving a sulfur amino acid-free diet

J. Lyons, A. Rauh-Pfeiffer, Y. M. Yu, X. M. Lu, D. Zurakowski, R. G. Tompkins, A. M. Ajami, V. R. Young, Leticia Castillo

Research output: Contribution to journalArticle

124 Scopus citations

Abstract

The availability of cysteine is thought to be the rate limiting factor for synthesis of the tripeptide glutathione (GSH), based on studies in rodents. GSH status is compromised in various disease states and by certain medications leading to increased morbidity and poor survival. To determine the possible importance of dietary cyst(e)ine availability for whole blood glutathione synthesis in humans, we developed a convenient mass spectrometric method for measurement of the isotopic enrichment of intact GSH and then applied it in a controlled metabolic study. Seven healthy male subjects received during two separate 10-day periods an L-amino acid based diet supplying an adequate amino acid intake or a sulfur amino acid (SAA) (methionine and cysteine) free mixture (SAA-free). On day 10, L-[1- 13C]cysteine was given as a primed, constant i.v. infusion (3 μmol · kg- 1 · h-1) for 6 h, and incorporation of label into whole blood GSH determined by GC/MS selected ion monitoring. The fractional synthesis rate (mean ± SD; day-1) of whole blood GSH was 0.65 ± 0.13 for the adequate diet and 0.49 ± 0.13 for the SAA-free diet (P < 0.01). Whole blood GSH was 1,142 ± 243 and 1,216 ± 162 μM for the adequate and SAA-free periods (P > 0.05), and the absolute rate of GSH synthesis was 747 ± 215 and 579 ± 135 μmol · liter-1 · day-1, respectively (P < 0.05). Thus, a restricted dietary supply of SAA slows the rate of whole blood GSH synthesis and diminishes turnover, with maintenance of the GSH concentration in healthy subjects.

Original languageEnglish (US)
Pages (from-to)5071-5076
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume97
Issue number10
DOIs
StatePublished - May 9 2000
Externally publishedYes

    Fingerprint

ASJC Scopus subject areas

  • General

Cite this