Sodium carboxymethyl cellulose (CMC) was used as the substrate to investigate the changes of kinetics, UV absorption spectra, UV-differential spectra, and fluorescence emission spectra of the enzyme in dimethyl sulfoxide solution (DMSO). Experiments indicated that the activity of eellulase decreased by 46. 78％ in 3％ solution. Km value rose from 2.500 mg/mi in phosphate buffer to 3.922 mg/mL in 3％ DMSO. UV absorption of peptide bonds changed slightly, but the UV absorption of amino acid Phe, Tyr, and Trp did not change. The UV differential spectra of cellulase in DMSO solution showed negative and positive peaks. The fluorescence emission spectra of cellulase did not change in DMSO solution. It was proved that dimethyl sulfoxide could change the structure of peptide chains to transform the conformation of cellulase molecules. Thus it decreased the affinity of the enzyme to their substrate and decreased the catalytic activity of the enzyme.%为了探索二甲基亚砜对纤维素酶催化活性的影响,以羧甲基纤维素钠(CMC)为底物来研究纤维素酶纯酶在二甲基亚砜中的动力学变化、紫外吸收光谱、紫外差示光谱和荧光发射光谱.实验表明:在3%的二甲基亚砜中,纤维素酶的催化活性下降了46.78%;其Km值从缓冲液中的2.500mg/mL上升到二甲基亚砜中的3.922mg/mL;在二甲基亚砜中,酶分子的肽键紫外吸收稍有改变,但其氨基酸基团的紫外吸收没有改变;其紫外差示光谱出现明显的正峰和负峰;其荧光发射光谱没有改变.研究结果证明:二甲基亚砜通过轻微改变酶分子的肽链结构,使分子构象改变,导致酶分子对底物的亲和力下降,从而降低其催化活性.
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