L-茶氨酸对α-淀粉酶和胰蛋白酶的抑制作用

Inhibitory effects of L-theanine on α-amylase and trypsin

以L-茶氨酸为原料,通过建立最佳酶促反应体系,采用非连续测定和作图法研究了L-茶氨酸对α-淀粉酶、胰蛋白酶的抑制作用及其动力学特征,为L-茶氨酸的深层开发利用提供参考。结果表明,L-茶氨酸对α-淀粉酶和胰蛋白酶的抑制效果均与其质量浓度呈正比,在底物质量浓度1%、体系添加顺序为酶与抑制剂在37℃预热5 min后加入底物的条件下,L-茶氨酸抑制α-淀粉酶的最优条件为α-淀粉酶质量浓度0.018mg/mL、反应时间3min,IC_(50)为26.078mg/mL,当酶量为18 518.52U时,α-淀粉酶的K_m为2.247mg/mL;在底物质量浓度1%、体系添加顺序为胰蛋白酶与抑制剂在40℃预热5min后加入底物的条件下,L-茶氨酸抑制胰蛋白酶的最优条件为胰蛋白酶质量浓度0.252mg/mL、反应时间15min,IC_(50)为196.299 mg/mL,当酶量为1 055 931 U时,胰蛋白酶的K_m为5.189mg/mL。说明L-茶氨酸对α-淀粉酶和胰蛋白酶均有一定的抑制作用,且抑制α-淀粉酶的效果较好。

The inhibitory effects of L-theanine on the activities ofα-amylase and trypsin were studied by establishing the best reaction system and adopting research method on graph in order to provide reference for the deep development of L-theanine.The results showed that the inhibitory effects of L-theanine on both enzyme activities were positively associated with its concentration.IC_（50）（26.078mg/mL）of L-theanine on the activities ofα-amylase was achieved by prewarming enzyme at a concentration of 0.018mg/mL in the presence of L-theanine at 37℃for 5min before addition of 1% starch and allowing reaction to proceed for 3min.K_m ofα-amylase was 2.247 mg/mL on the premise that the enzyme amount was 18 518.52 U.L-theanine exhibited the half inhibition on trypsin（196.299mg/mL）by prewarming their mixture at 40 ℃for 5min followed by addition of 1%casein as the substrate and permitting the reaction for 15 min.When the amount of enzyme was 1 055 931 U,K_m of trypsin was 5.189 mg/mL.Statistics results showed that the inhibitory effect of L-theanine on the activity ofα-amylase was superior than that of trypsin.