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l ‐Lactate generates hydrogen peroxide in purified rat liver mitochondria due to the putative l ‐lactate oxidase localized in the intermembrane space
Author(s) -
de Bari Lidia,
Valenti Daniela,
Atlante Anna,
Passarella Salvatore
Publication year - 2010
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2010.03.038
Subject(s) - intermembrane space , biochemistry , submitochondrial particle , hydrogen peroxide , lactate dehydrogenase , respiratory chain , peroxisome , oxidase test , chemistry , nad+ kinase , mitochondrion , cytosol , oxygen , mitochondrial matrix , mitochondrial intermembrane space , enzyme , organic chemistry , bacterial outer membrane , escherichia coli , gene
In order to ascertain whether and how mitochondria can produce hydrogen peroxide (H 2 O 2 ) as a result of l ‐lactate addition, we monitored H 2 O 2 generation in rat liver mitochondria and in submitochondrial fractions free of peroxisomal and cytosolic contamination. We found that H 2 O 2 is produced independently on the respiratory chain with 1:1 stoichiometry with pyruvate, due to a putative flavine‐dependent l ‐lactate oxidase restricted to the intermembrane space. The l ‐lactate oxidase reaction shows a hyperbolic dependence on l ‐lactate concentration and is inhibited by NAD + in a competitive manner, being the enzyme different from the l ‐lactate dehydrogenase isoenzymes as shown by their pH profiles.