效应剂和氢离子浓度对玉米绿苗和黄化苗PEP羧化酶活性的协同作用

Cooperative Effects of Effectors and pH on the Activity of Phosphoenolpyruvate Carboxylase from Green and Etiolated Maize Leaves

以玉米为材料，研究了效应剂和ｐＨ对绿色和黄化玉米ＰＥＰ羧化酶活性的协同作用，发现绿苗和黄化苗中ＰＥＰ羧化酶对效应剂的敏感性不同，前者比后者对Ｇ６Ｐ、Ｇｌｙ敏感，而后者比前者对Ｍａｌ敏感。黄化苗经３ｈ光处理后，其ＰＥＰ羧化酶对Ｇ６Ｐ的敏感性与绿苗趋于相同。同时发现ｐＨ不同，ＰＥＰ羧化酶对效应剂的敏感性也不同，低ｐＨ比高ｐＨ时酶对效应剂更敏感。根据绿苗和黄化苗ＰＥＰ羧化酶活性和对效应剂敏感性的差异推测黄化苗中ＰＥＰ羧化酶的主要功能不是同化ＣＯ２。

In this paper, the cooperative effects of effectors and pH on the activity of PEPCase and the differences in sensitivities of PEPCase to effectors in green and etiolated maize leaves were studied. It was discovered that the PEPCase in green leaves was more sensitive to G6P and Gly, but less sensitive to Mal than that in etiolated leaves (Fig 1,2,3,4).When etiolated leaves was exposed to light(3000 lx)for 3 hours, the sensitivity of PEPCase to G6P tended to be similar to that in green leaves(Fig 1)The PEPCase in green or etiolated leaves also showed different sensitivities to G6P,Gly and Mal when assayed at different PH, being more sensitive to G6P,Gly and Mal at lower PH (7.4) than at higher ph(9.2)(Fig,2,3,4).The sensitivity of PEPCase to G6P in green leaves at pH9.2 was similar to that in etiolated leaves at pH7.4(Fig.2).This suggested the involvement of cooperative effects of effector and pHon the activity of PEPCase. The reguiatory properties of PEPCase in etiolated leaves by effectors showed that the major function of PEPCase in etiolated leaves might be not to fix CO2 for photosynthesis.