Abstract
The manganese superoxide dismutase (Mn-SOD) converts super-oxide 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.
Original language | English (US) |
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Pages (from-to) | 405-416 |
Number of pages | 12 |
Journal | Amino Acids |
Volume | 22 |
Issue number | 4 |
DOIs | |
State | Published - 2002 |
Keywords
- Amino acids
- Calcium
- Heart mitochondria
- Liver mitochondria
- Magnesium
- Mn-SOD
- Superoxide anion
ASJC Scopus subject areas
- Biochemistry
- Clinical Biochemistry
- Organic Chemistry