l-Cysteine metabolism via 3-mercaptopyruvate pathway and sulfate formation in rat liver mitochondria

T. Ubuka, Jun Ohta, W. B. Yao, T. Abe, T. Teraoka, Y. Kurozumi

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Abstract

We have studied the 3-mercaptopyruvate pathway (transamination pathway) of l-cysteine metabolism in rat liver mitochondria. l-Cysteine and other substrates at 10 mM concentration were incubated with mitochondrial fraction at pH 8.4, and sulfate and thiosulfate were determined by ion chromatography. When l-cysteine alone was incubated, sulfate formed was 0.7 μmol per mitochondria from one g of liver per 60 min. Addition of 2-oxoglutarate and GSH resulted in more than 3-fold increase in sulfate formation, and thiosulfate was formed besides sulfate. The sum (A + 2B) of sulfate (A) and thiosulfate (B) formed was approximately 7-times that with l-cysteine alone. Incubation with 3-mercaptopyruvate resulted in sulfate and thiosulfate formation, and sulfate was formed with thiosulfate. These reactions were stimulated with glutathione. Sulfate formation from l-cysteinesulfinate and 2-oxoglutarate was not enhanced by glutathione and thiosulfate was not formed. These findings indicate that l-cysteine was metabolized and sulfate was formed through 3-mercaptopyruvate pathway in mitochondria.

Original languageEnglish
Pages (from-to)143-155
Number of pages13
JournalAmino Acids
Volume2
Issue number1-2
DOIs
Publication statusPublished - Feb 1992

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Keywords

  • 3-Mercaptopyruvate pathway
  • Amino acids
  • Cysteine metabolism
  • Glutathione
  • Mitochondria
  • Sulfate formation

ASJC Scopus subject areas

  • Endocrinology
  • Clinical Biochemistry
  • Biochemistry

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