Summary.
The manganese superoxide dismutase (Mn-SOD) converts superoxide anions to hydrogen peroxide plus oxygen, providing the first line of defense against oxidative stress in mitochondria. Heart mitochondria exhibited higher Mn-SOD activity than liver mitochondria. In mitochondria from both tissues Mn-SOD activity decreased after incubation at low oxygen concentration (hypoxic mitochondria). The effects of free Ca2+ ([Ca2+]f) and free Mg2+ ([Mg2+]f) on normoxic and hypoxic mitochondria from either organ were tested. In normoxic mitochondria from either tissue, both [Ca2+]f and [Mg2+]f activated the enzyme, although [Mg2+]f was less efficient as an activator and the effect was lower in heart than in liver mitochondria. When added simultaneously, high [Ca2+]f and [Mg2+]f exhibited additive effects which were more pronounced in heart mitochondria and were observed regardless of whether mitochondria had been incubated under normal or low oxygen. The data suggest that [Ca2+]f plays a role in regulating Mn-SOD in concert with the activation of aerobic metabolism.
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Received April 2, 2001 Accepted August 16, 2001
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Pérez-Vázquez, V., Ramírez, J., Aguilera-Aguirre, L. et al. Effect of Ca2+ and Mg2+ on the Mn-superoxide dismutase from rat liver and heart mitochondria. Amino Acids 22, 405–416 (2002). https://doi.org/10.1007/s007260200024
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DOI: https://doi.org/10.1007/s007260200024