论文部分内容阅读
目的：研究脲对人胎盘碱性磷酸酶构象与活力的影响。方法：用分光法测定不同浓度脲溶液中的紫外差光谱及活力；荧光法测其荧光光谱。结果：低浓度脲（＜2．0 mol／L），酶的差光谱在262 nm出现负峰；荧光强度下降，发射峰位蓝移；脲浓度为0．5 mol／L时，酶活力仍维持在原有水平，此后随脲浓度增加，酶活力下降。继续提高脲浓度，差光谱在276 nm出现正峰；荧光强度回升，发射峰位红移；酶活力迅速下降。当脲浓度高达8．0 mol／L时，差光谱在262 nm又出现负峰；荧光强度继续增强，发射峰位还在红移；酶仍有部分活力。结论：酶活力变化慢于其构象变化，但酶活性部位较整个分子而言更易受到脲的扰乱。
Objective: To study the effect of urea on the conformation and activity of human placental alkaline phosphatase. Methods: The ultraviolet spectrum and activity in different concentrations of urea solution were determined by spectrophotometry. The fluorescence spectra were measured by fluorescence method. Results: At low concentration of urea (<2.0 mol / L), the difference spectrum of enzyme showed a negative peak at 262 nm, the fluorescence intensity decreased and the emission peak shifted blue. When the concentration of urea was 0.5 mol / L, Maintained at the original level, with increasing urea concentration, enzyme activity decreased. Continue to raise the urea concentration, the difference spectrum at 276 nm positive peak; fluorescence intensity rose, the emission peak position redshift; enzyme activity decreased rapidly. When the concentration of urea was as high as 8.0 mol / L, the difference spectrum showed a negative peak at 262 nm; the fluorescence intensity continued to increase and the emission peak was still red-shifted; and the enzyme still had some activity. CONCLUSIONS: The changes in enzyme activity are slower than those in conformational changes, but the enzymatic site is more susceptible to urea disruption than the entire molecule.