稀土离子La^(3+)对精氨酸酶的抑制作用

Inhibition of the Arginase Catalyzed Hydrolysis of L-Arginine by La^(3+)

在37℃、pH=9.4、40 mmol/L的巴比妥钠-盐酸缓冲体系中,利用微量热法研究了稀土离子镧对牛肝精氨酸酶催化L-精氨酸水解反应的影响。实验结果表明,镧离子对精氨酸酶催化反应存在着明显的抑制作用,其抑制类型为非竞争性可逆抑制,求得抑制常数K1为2.74×10-4mol/L。根据其抑制类型和离子半径,推测镧离子与精氨酸酶的结合位置远离酶的活性中心。

The inhibitive role of lanthanum ion on the arginase catalyzed hydrolysis of L-arginine was studied by microcalorimetry in a 40 mmol/L sodium barbiturate-hydrochloric acid buffer solution at 37 ℃ and pH of 9.4.The results indicated La3＋ has remarkable inhibition effect on the catalytic activity of arginase and the inhibitory type belongs to the reversible non-competitive inhibition with the inhibition constant of 2.74×10-4 mol/L.On the basis of the inhibition type and ion radius,we suggested that the binding site of La3＋ to arginase is far from the active site of arginase.