A Specific Ascorbate Free Radical Reductase Isozyme Participates in the Regeneration of Ascorbate for Scavenging Toxic Oxygen Species in Potato Tuber Mitochondria
Author(s) -
Silvana De Leonardis,
Giulia De Lorenzo,
Giuseppe Borraccino,
Silvio Dipierro
Publication year - 1995
Publication title -
plant physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.554
H-Index - 312
eISSN - 1532-2548
pISSN - 0032-0889
DOI - 10.1104/pp.109.3.847
Subject(s) - biochemistry , enzyme , cytosol , mitochondrion , glutathione reductase , ascorbic acid , isozyme , chemistry , reductase , glutathione , food science , glutathione peroxidase
Ascorbate free radical (AFR) reductase from isolated potato tuber (Solanum tuberosum L.) mitochondria was studied. The enzyme was purified to homogeneity and its physico-chemical and kinetic properties were compared to those of the cytosolic enzyme. The molecular mass of the mitochondrial enzyme was about 54 kD, whereas that of the cytosolic enzyme was about 42 kD. The Km values of mitochondrial AFR reductase for NADH, NADPH, and AFR were higher than those of the cytosolic enzyme. Moreover, the mitochondrial enzyme proved to be less sensitive to inhibition by sulfhydryl reagents. It was concluded that the ascorbate involved in the scavenging of toxic oxygen species in potato tuber mitochondria is regenerated via the ascorbate-glutathione pathway, in which a specific AFR reductase isozyme participates.
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