光/暗对玉米叶片果糖-6-磷酸激酶-2和果糖-2,6-二磷酸酯酶活力的影响

Light/Dark Modulation of the Activities of Fructose-6-Phosphate 2-Kinase/Fructose 2, 6-Bisphosphatase from Maize Leaves

比较了照光和黑暗条件下玉米叶片果糖—6—磷酸激酶—2(PFK-2)和果糖—2,6—二磷酸酯酶(FBPase-2)的活力变化。当玉米植株从暗中转入光下后,其叶片PFK—2的活力随光照时间的延长而逐渐降低,而FBPase-2活力变化不明显;从光下转入暗后叶片PFK-2活力明显上升,FBPase-2活力仍无明显变化;其PFK-2/FBPase-2比值在光处理时下降,暗处理时上升。同时叶片中果糖—2,6—二磷酸的含量与PFK-2/FBPase-2活力比值的变化趋势一致。连续光照 20 h,PFK-2活力持续下降,表明PFK-2的光钝化现象与玉米植株的昼夜节律变化无关。

Light and dark modulation of theactivities of fructose-6- phosphate 2-kinase (PFK-2)/fructose 2, 6-bisphos-phatase (FBPase-2) in maize leaveshave been compared. The activity ofPFK-2 from leaves decreased graduallyduring illumination of the plants, butincreased slowly when the plants wereplaced in the dark. During the wholeperiod of light/dark(12 h/12 h) treat-ment, the activity of FBPase-2 fromleaves changed little while the PFK-2/FBPase-2 ratio and F2, 6P_2 levelschanged in parallel to the activity ofPFK-2. During 20 h of continuing illumi-nation, the activity of PFK-2 also de-creased gradually, suggesting that theincrease of PFK-2 activity in the darkmight not be due to the diurnal rhythmof the plant. The low molecular weightcomponents in the crude extract did notaffect the above results, even thoughthey changed the emzyme activities insome way.