Abstract:

This study aimed to characterize the redox stability of oxymyoglobin from bovine heart. Myoglobin was isolated
by ammonium sulphate precipitation (75%—100% saturation), followed by Sephadex G-75 chromatography. Its purity
was identified by scanning spectrophotometry. The pH and thermal stability of oxymyoglobin were tested over a pH range
of 3.0—11.0 and a temperature range of 20—60 ℃. In addition, oxymyoglobin was incubated with 4-hydroxy-2-nonenal
(HNE) and lactic acid, the redox stability of myoglobin was expressed by metmyoglobin percentage. The results showed
that the stability of oxymyoglobin was decreased and the formation of metmyoglobin increased with increasing temperature.
Metmyoglobin had the highest stability at pH 7.0, where the characteristic absorption peak of myoglobin disappeared. When
compared with the control group, HNE improved the accumulation of metmyoglobin, while lactic acid decreased the accumulation of
metmyoglobin. Myoglobin redox stability in neutral and alkaline environment was significantly higher than that in acid environment
(P ＜ 0.01). Moreover, HNE improved the autoxidation of oxymoglobin, while lactate inhibited the autoxidation of oxymoglobin.

Key words: oxymyoglobin, metmyoglobin, redox stability, thermostability