The relative effectiveness of human plasma glutathione peroxidase as a catalyst for the reduction of hydroperoxides by glutathione

Sylvia A. Howard, Wayne C. Hawkes

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

To reveal clues to the function of human plasma glutathione peroxidase (GPx), we investigated its catalytic effectiveness with a variety of hydroperoxides. Comparisons of hydroperoxides as substrates for plasma GPx based on the ratio of V(max)/K(m) were blocked by the limited solubility of the organic hydroperoxides, which prevented kinetic saturation of the enzyme at the chosen glutathione concentration. Therefore, we compared the hydroperoxides by the fold increase in the apparent first-order rate constants of their reactions with glutathione owing to catalysis by plasma GPx. The reductions of aromatic and small hydrophobic hydroperoxides (cumene hydroperoxide, t-amyl hydroperoxide, t-butyl hydroperoxide, paramenthane hydroperoxide) were better catalyzed by plasma GPx than were reductions of the more 'physiological' substrates (linoleic acid hydroperoxide, hydrogen peroxide, peroxidized plasma lipids, and oxidized cholesterol).

Original languageEnglish (US)
Pages (from-to)127-136
Number of pages10
JournalBiological Trace Element Research
Volume61
Issue number2
StatePublished - 1998
Externally publishedYes

Fingerprint

Plasma (human)
Glutathione Peroxidase
Hydrogen Peroxide
Glutathione
Catalysts
Plasmas
tert-Butylhydroperoxide
Saturation (materials composition)
Substrates
Catalysis
Rate constants
Solubility
Cholesterol
Lipids
Kinetics
Enzymes

Keywords

  • Enzyme function
  • Extracellular glutathione peroxidase
  • Hydroperoxide
  • Plasma glutathione peroxidase
  • Substrate preference

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

The relative effectiveness of human plasma glutathione peroxidase as a catalyst for the reduction of hydroperoxides by glutathione. / Howard, Sylvia A.; Hawkes, Wayne C.

In: Biological Trace Element Research, Vol. 61, No. 2, 1998, p. 127-136.

Research output: Contribution to journalArticle

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