零下低温对小麦线粒体磷酸运转功能的影响

EFFECT OF TEMPERATURE BELOW 0℃ (-15℃) ON FUNCTION OF PHOSPHATE TRANSFER OF ISOLATED MITOCHONDRIA FROM WHEAT

试验用铵膨胀法研究了小麦线粒体磷酸转运体对-15℃低温的反应。结果表明:-15℃低温使小麦离体线粒体磷酸转运体活性受到钝化,Km值增加,未锻炼(在25℃下生长5天)的品种之间对-15℃低温的反应基本上一致。-15℃低温还使线粒体蛋白质的巯基含量减少。巯基含量的减少与磷酸运转功能的下降呈极显著的正相关(r=0.986)。锻炼减缓了巯基含量减少的变化。巯基修饰剂NEM可抑制磷酸转运体的活性。试验提供了低温伤害膜功能性蛋白质的证据。

The effect of temperature below 0℃ (-15℃) on phosphate carrier of isolated mitochondria from etiolated wheat seedlings [Triticum aestivum L. cv Dongfanghong No. 3(freezing-tolerance) and Fengqiang No. 3 (freezing-sensitive)] were studied as ammonia swelling technique. The results obtained are summarized as follows: (1) the phosphate carrier activity of isolated mitochondria was deactivated, and its Km values were increased by temperature below 0℃ (-15℃). No signi- ficant differences in the phosphate transfer functions were observed between sensitive and tolerance cultivars for no hardening (grown at 25℃ for 5days) after -15℃ treatment; (2) the content of -SH group of mitochondria protein was decreased by temperature below 0℃(-15℃). There was a positive interrelation between the content of -SH group and activity of phosphate carrier for isolated mitochondria irom Fengqiang No.3, and interrelated coefficient (r=0.986)was highest significant. The decrease in the content of -SH group was slow downed, phosphate carriers of mitochondria of two cultivars were inhibited by hardening and sulfhydryl regent, NEM, respectively. The experimental result provides an evidence for that functional protein combined with biomembrane injuried by temperature below 0℃.