荧光探针Tb(Ⅲ)与葡萄糖淀粉酶的络合作用

The Complexing of Glucoamylase with Fluorescent Probe Tb(Ⅲ)

以Tb(Ⅲ)作荧光探针探索葡萄糖淀粉酶分子与该离子的成键位置数、成键环境及键合Tb(Ⅲ)的解离常数K_D。

The bonding properties, enviroment and the dissociation constant of glucoamylase with Tb( Ⅲ) as a fluorescent probe were investigated. The results show that an enzyme molecule could be bonded with 4 Tb(Ⅲ) at 20℃> pH 4.6, and the bonding site is in the free carboxyl groups which belong to Glu/Asp, KD was calculated to be 2. 5×10-4 mol/L. The fluorescence intensity of Tb(Ⅲ) is greatly sensitized by the enzyme to 1 000 folds at 545 nm. On the contrary, the fluorescence intensity of glucoamylase at 345 nm is quenched and the quenching efficiency is calculated to be 0. 75%.