离子液体[Emim]DEP对纤维素酶的影响研究

Influence of ionic liquid[Emim]DEP on the cellulase

研究了[Emim]DEP、[Emim]Ac和[Bmim]Cl对3,5-二硝基水杨酸（DNS）法测还原糖的影响,结果表明当离子液体浓度为0~20%（w/v,质量体积比,下同）,3种离子液体对测量结果几乎无影响。在此基础上,比较了这3种离子液体对纤维素酶活力的影响。在3种离子液体中,[Emim]DEP对纤维素酶的抑制作用最小,但其浓度不宜超过10%以获得较高的相对酶活力。随后考察了纤维素酶在[Emim]DEP中的稳定性,相对酶活力总体上随着温度的升高和保存时间的延长而下降,但当[Emim]DEP浓度为5%时,在4℃保存24h后纤维素酶的相对活力却有所提高。纤维素酶在[Emim]DEP溶液中的紫外吸收光谱表明,[Emim]DEP使纤维素酶肽链的结构发生改变,并改变了酶分子构象,导致酶分子对底物的亲和力下降,影响了纤维素酶活力。

The effects of [Emim]DEP,[Emim]Ac and [Bmim]C1 on the 3,5-dinitrosalic acid（DNS） reducing sugar assay were assessed. No interference was observed in the assay for these ionic liquids（ILs） concentration from 0% to Z0 %. Based on the result, the influences of these ILs on the cellulase activity were compared. In three ILs, the inhibition of [Emim]DEP on the cellulase activity was the smallest, but its concentration should not exceed 10% in order to maintain a high relative enzyme activity. Then,the stability of cellulase in the presence of different concentrations of [Emlm]DEP was investigated. Generally, the relative enzyme activity decreased with the increase of temperature and incubation time. But when the concentration of [Emim]DEP was 50% ,the relative activity of cellulase was increased after pre-incubation at 4℃ for 24h. The UV absorption spectrum of cellulase in [Emirn]DEP solution showed that [Emim]DEP could change the structure of peptide chains to transform the conformation of cellulase molecules. Thus it decreased the affinity of enzyme to their substrate and decreased the catalytic activity of enzyme.