重组毛白杨4-香豆酸:辅酶A连接酶催化不同肉桂酸衍生物的酶促动力学研究

4-香豆酸:辅酶A连接酶是杨树木质素合成途径的关键酶之一,催化维管植物木质素合成羟基肉桂酸及其衍生物辅酶A酯化合物的形成.对毛白杨的重组Pt4CL1蛋白的不同肉桂酸衍生物底物的酶促动力学进行了分析,Pt4CL1对肉桂酸、4-香豆酸、咖啡酸、阿魏酸具有催化活性,其中的4-香豆酸、咖啡酸、阿魏酸,Km(μM)值分别为55.02±3.5、52.94±6、44.62±4,Vmax(nM.S-1)值分别为4.23±0.27、4.12±0.11、2.16±0.07;4-香豆酸,咖啡酸,阿魏酸的Kcat(S-1)值分别为44.73×10-3、43.57×10-3、7.61×10-3;对4-香豆酸,咖啡酸,阿魏酸的Kenz(M-1.S-1)值分别为823、812.98、170.55.Pt4CL1对肉桂酸的催化能力很弱,而对芥子酸没有催化活性.结果表明,Pt4CL1对4-香豆酸的催化效率最高,对咖啡酸的催化效率略低于4-香豆酸,而对阿魏酸的催化效率最低,对咖啡酸的催化效率略有很高的转化效率.

Kinetic Parameters of a Recombinant 4-Coumarate: Coenzyme A Ligase from Populus Tomentosa

Coenzyme A ligase as a key enzyme of lignin synthesize catalyzes the forming of the corresponding CoA thioesters of cinnamate and its hydroxylated derivatives in vascular plants.Kinetic constants(Km and Vmax) for Pt4CL1 isoform were measured under the standard conditions.Research Shows:to p-coumaric,the Km(μM) of Pt4CL1 is 55.02±3.5;to caffeic,the Km(μM) of Pt4CL1 is 52.94±6;to ferulic,the Km(μM) of Pt4CL1 is 44.62±4.The Vmax(nM/S) of p-coumaric,caffeic,ferulic are 4.23±0.27,4.12±0.11,2.16±0.07.And the Kcat(1/s) of Pt4CL1 to the three substrates are 44.73×10-3,43.57×10-3,7.61×10-3;The Kenz(M-1s-1) of Pt4CL1 to the three substrates are 823,812.98,170.55.The kinetic constants show that p-coumaric have the biggest conversion efficiency when the reaction were performed with Pt4CL1,So,p-coumaric is the optimum substrate to the Pt4CL1 enzyme.