底物、末端产物对离体银杏叶苯丙氨酸解氨酶活性的影响

苯丙氨酸处理浓度高于2.5mmol/L时抑制酶活性,低于2.5mmol/L时促进酶活性,诱导酶活性最强的是1.25mmol/L苯丙氨酸处理。4个浓度的反式肉桂酸处理都能抑制酶活性,100mg/L反式肉桂酸抑制酶活性作用最强。3,5-二氢肉桂酸除100mg/L微弱地增加酶活性外,其余都抑制酶活性,抑制酶活性最强的为200mg/L3,5-二氢肉桂酸处理。阿魏酸除100mg/L浓度增加酶活性外,其它浓度处理都降低酶活性,50mg/L抑制酶活性最强。4个浓度的4,5,7-三羟黄烷酮(Naringenin)都能抑制酶活性,其中,6.25mg/L抑制能力最强。

Effects of Substrate and Terminal Products on the Phenylalanine Ammonia-lyase (PAL) Activities in in vitro leaves of Ginkgo biloba

Experiments indicated that phenylalanine (Phe) inhibited phenylalanine ammonia-lyase (PAL) activities when its concentrations was more than 2.5 mmol/L, whereas when it was equal or lower than 2.5 mmol/L,the activities were enhanced. The treatment with 1.25 mmol/L of Phe showed the activities of PAL were greatly increased. All the 4 concentrations of trans-cinnamic acid inhibited the PAL activities, but it was inhibited most strongly by the 100 mg/L. Besides the concentration of 100 mg/L,all the other treatments of 3,5-dihydro-cinnamic acid inhibited PAL activities,and 200 mg/L effect was the strongest. Ferulic acid of all concentrations but 100 mg/L,inhibited PAL activities,and 50 mg/L effect was the strongest. Naringenin of 4 concentration treatments inhibited PAL activities and 6.25 mg/L was the strongest.