白三叶超氧化物歧化酶性质初步研究

Preliminary study on the characteristics of superoxide dismutase in Trifolium repens

白三叶叶片超氧化物歧化酶（ＳＯＤ）粗酶提取液中既含有ＣｕＺｎＳＯＤ，又含有ＭｎＳＯＤ；其同工酶谱带共有５条，其中迁移率为０７１８７的第４条谱带是ＭｎＳＯＤ，其余都是ＣｕＺｎＳＯＤ。粗酶液具有较高的热稳定性，水浴中保温１５ｍｉｎ处理时，活性半抑制温度约为６３℃；粗酶液在恒温水浴中保温处理，６０℃条件下的活性半衰期约为３７７ｍｉｎ。在变性剂ＳＤＳ作用下，第１，２条ＣｕＺｎＳＯＤ活性谱带与第４条ＭｎＳＯＤ活性谱带活力丧失，而第３，５条ＣｕＺｎＳＯＤ活性谱带活性变化较小；在β巯基乙醇作用下，第１，２，３条ＣｕＺｎＳＯＤ活性谱带全部消失，而第４条ＭｎＳＯＤ活性谱带变宽，并出现了迁移率为０５３１２的新活性谱带，第５条ＣｕＺｎＳＯＤ活性谱带则仍然保留；在８ｍｏｌ／Ｌ脲存在时，ＭｎＳＯＤ活性谱带消失，ＣｕＺｎＳＯＤ活性谱带几乎不受影响；在ＳＯＳ和β巯基乙醇的共同作用下，除第５条活性谱带外，其余ＳＯＤ同工酶谱带几乎全部消失。

A study was made to determine some characteristics of superoxide dismutase(SOD) in white clover(Trifolium repens L. cv. Louisiana K 57114 ). Both types of CuZn SOD and Mn SOD were detected and five isozyme bands found by polyacrylamide gel electrophoretic analysis in the SOD crude etract of white clover leaves with results showing that, the fourth band of which with the morbility of 0 7187 is Mn SOD and others are CuZn SOD. The test on thermal stability of the SOD crude extract indicated that, when incubated for 15 min in water bath, the catalytic activity half inhibitory temperature is around 63℃; When incubated under constant temperature of 60℃ in water bath, its half life of catalytic activity is about 37 7min. SDS, a denaturant , results in loss of catalytic activities of the CuZn SOD of the first and second electrophoretic bands and the Mn SOD of the fourth band, but little change of the CuZn SOD of the third and fifth bands. When treated with β mercaptoethenol, the first, second and third bands disappear, while the fourth band widens and another new band with the morbility of 0 5312 presents and the fifth band maintains. However, when treated with both chemicals of SDS and β mercaptoethenol, all electrophoretic bands disappear except the fifth one. When exposed to 8 0mol/L urea, the Mn SOD inactivates, while CuZn SODs are little affected.