黑腹果蝇中的超氧化物歧化酶：同工酶变体的生化与结构特征
Superoxide dismutase in Drosophila melanogaster: biochemical and structural characterization of allozyme variants.
作者信息
Lee Y M, Misra H P, Ayala F J
出版信息
Proc Natl Acad Sci U S A. 1981 Nov;78(11):7052-5. doi: 10.1073/pnas.78.11.7052.
Superoxide dismutase (SOD; superoxide:superoxide oxidoreductase, EC 1.15.1.1) is known to be polymorphic in many organisms; in Drosophila, the degree of polymorphism has a wide range of variation from locality to locality within a given species. We have thoroughly purified from D. melanogaster the two common electromorphs, SODS and SODF. These differ in properties such as isoelectric point, specific activity, rate constant, thermostability, and amino acid composition. The specific activity is three times greater in SODS than in SODF, but the latter is more thermostable. In strains from California, SODS differs from SODF by at least one amino acid substitution: lysine in SODS is replaced by either aspartic acid or asparagine in SODF. This difference is consistent with the electrophoretic mobility and isoelectric points of the two electromorphs. In strains from Africa, SODS and SODF differ by two amino acid substitutions (histidine and proline in SODS vs. serine and either glutamic acid or glutamine in SODF) in addition to the one distinguishing the California strains. Thus the SODF electromorphs from California and from Tunisia, in spite of their identical electrophoretic mobility, differ by at least two amino acid substitutions.
超氧化物歧化酶（SOD；超氧化物：超氧化物氧化还原酶，EC 1.15.1.1）在许多生物体中已知具有多态性；在果蝇中，多态性程度在给定物种内的不同地点之间有广泛的变化范围。我们已经从黑腹果蝇中彻底纯化出两种常见的电泳变体，SODS和SODF。它们在等电点、比活性、速率常数、热稳定性和氨基酸组成等性质上有所不同。SODS的比活性比SODF高三倍，但后者更耐热。在来自加利福尼亚的品系中，SODS与SODF至少有一个氨基酸替换不同：SODS中的赖氨酸被SODF中的天冬氨酸或天冬酰胺取代。这种差异与两种电泳变体的电泳迁移率和等电点一致。在来自非洲的品系中，除了区分加利福尼亚品系的那个氨基酸替换外，SODS和SODF还有两个氨基酸替换不同（SODS中的组氨酸和脯氨酸与SODF中的丝氨酸以及天冬氨酸或谷氨酰胺）。因此，来自加利福尼亚和突尼斯的SODF电泳变体，尽管它们的电泳迁移率相同，但至少有两个氨基酸替换不同。
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