Premium
The reaction of ascorbic acid with different heme iron redox states of myoglobin
Author(s) -
Giulivi Cecilia,
Cadenas Enrique
Publication year - 1993
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 - 10.1016/0014-5793(93)80651-a
Subject(s) - metmyoglobin , myoglobin , chemistry , ascorbic acid , redox , heme , hydrogen peroxide , photochemistry , hemeprotein , oxygen , electron transfer , inorganic chemistry , organic chemistry , enzyme , food science
The interaction of ascorbate with different heme iron redox states of myoglobin (ferrylmyoglobin, Fe IV =O; metmyoglobin, Fe III ; and oxymyoglobin Fe II O 2 ) was examined by e.s.r. and absorption spectroseopy. The reaction of ascorbate with ferryl‐ or met‐myoglobin resulted in ascorbyl radical production. The interaction of ascorbate with oxymyoglobin proceeded with formation of ascorbyl radical, hydrogen peroxide, and an overall oxidation of oxymyoglobin to metmyoglobin. The latter reaction proceeded via an oxoferryl complex intermediate ‐ corresponding to ferrylmyoglobin and identified by treatment of the reaction mixture with Na 2 S. These observations are consistent with a concerted electron transfer mechanism, whereby the two electrons required for the reduction of oxygen to hydrogen peroxide are donated by ascorbic acid and the heme iron. The antioxidant and prooxidant aspects of these redox transitions are discussed in terms of their kinetic properties.