Hassan H M
Department of Food Science, North Carolina State University, Raleigh 27695-7624.
Free Radic Biol Med. 1988;5(5-6):377-85. doi: 10.1016/0891-5849(88)90111-6.
The past two decades have witnessed an explosion in our understanding of oxygen toxicity. The discovery of superoxide dismutases (SODs) (EC.1.15.1.1), which specifically catalyze the dismutation of superoxide radicals (O2-) to hydrogen peroxide (H2O2) and oxygen, has indicated that O2- is a normal and common byproduct of oxygen metabolism. There is an increasing evidence to support the conclusion that superoxide radicals play a major role in cellular injury, mutagenesis, and many diseases. In all cases SODs have been shown to protect the cells against these deleterious effects. Recent advances in molecular biology and the isolation of different SOD genes and SOD c-DNAs have been useful in proving beyond doubt the physiological function of the enzyme. The biosynthesis of SODs, in most biological systems, is under rigorous controls. In general, exposure to increased pO2, increased intracellular fluxes of O2-, metal ions perturbation, and exposures to several environmental oxidants have been shown to influence the rate of SOD synthesis in both prokaryotic and eukaryotic organisms. Recent developments in the mechanism of regulation of the manganese-containing superoxide dismutase of Escherichia coli will certainly open new research avenues to better understand the regulation of SODs in other organisms.
在过去二十年里，我们对氧毒性的认识有了爆发式增长。超氧化物歧化酶（SODs）（EC.1.15.1.1）的发现，它能特异性催化超氧阴离子自由基（O2-）歧化为过氧化氢（H2O2）和氧气，这表明O2-是氧代谢的一种正常且常见的副产物。越来越多的证据支持超氧阴离子自由基在细胞损伤、诱变及许多疾病中起主要作用这一结论。在所有情况下，超氧化物歧化酶都已被证明能保护细胞免受这些有害影响。分子生物学的最新进展以及不同超氧化物歧化酶基因和cDNA的分离，对于毫无疑问地证明该酶的生理功能很有帮助。在大多数生物系统中，超氧化物歧化酶的生物合成受到严格控制。一般来说，暴露于升高的pO2、增加的细胞内O2-通量、金属离子扰动以及接触几种环境氧化剂，已被证明会影响原核生物和真核生物中超氧化物歧化酶的合成速率。大肠杆菌含锰超氧化物歧化酶调控机制的最新进展，肯定会为更好地理解其他生物中超氧化物歧化酶的调控开辟新的研究途径。
