Abstract: Result of the research on inactivation of phosphoenolpyruvate carboxylase(PEP Case) in maize leaves at low temperature showed that with the passage of preservation time of PEPCase in maize leaves in vitro at low temperature,its activity and sensitivity to such effectors as G- 6- P.Gly and 2,4- D obviously dropped.Glyeerol (20%)could protect the PEPCase activity and sensitivity to 2,4-D.when the PEPCase was stored, in low temperature.G-6-P had no the effects alone,but when the G-6-P being in the same concentration was used with Gly and glycerol,it could protect PEPCase activity and sensitivity ro 2.4-D,and the effect was greater than that of glycerol in the same concentration.NaCl showed inhibition effect on the PEPcase activity,but had less effect on the PEPCase sensitivity to the effectors,and could not protect the activity and sensitivity to the effectors when PEPCase was preserved in low temperature.Under the conditions, the PEPCase showed inactivation and less sensitivity to the effectors.The above, reagents displayed the same protective capability for the PEPCase activity and sensitivity to the effectors in petiod of preservation in Sow temperature.This indicated that less sensitivity cf PEPCase to effectors at low temperature was related to the low-temperature inaccivation.

Key words: Maize (PEP carboxylase, Low temperature, Sensitivity, Effector