人类胎盘碱性磷酸酶在脲变性时构象与活力的变化  

The changes of conformation and catalytic activity of human placental alkaline phosphatase during urea denaturation

作　　者：耿芳宋[1] 王秀丽[1] 童家明 刘洪明 

机构地区：[1]青岛大学医院生物化学教研室,山东青岛266021 [2]青岛大学医院物理教研室,山东青岛266021

出　　处：《中国医学物理学杂志》2000年第3期165-167,共3页Chinese Journal of Medical Physics

基　　金：山东省卫生厅资助项目(95036)

摘　　要：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。： Purpose：To study the effect of urea on the conformation and activity of human placental alkaline phosphatase(PLAP, E．C．3．1．3．1．Method： SPECTrophotometry was used to measuer the activity and ultraviolet difference spectra,fluorometry was used to observe flurescence spectra of PLAP in urea solutions of different concentrations． Results： Urea concentrations lower than 2．0 mol／L,the difference spectra show a negative peak around 262 nm；the fluorescence intensity decreases with a blue shift of emission maximum ；while the enzyme activity decreased after a stagnant stage below 0．5 mol／L of urea, during this stage, the emzyme activity maintained the original level． A urea concentrations higher than 2．0mol／L,the difference spectra show a positive peak around 276 nm； the fluorescence emission maximum of PLAP red shifts with increasing intensity in urea solutions of increasing concentrations, and PLAP activity rapidly decreased． When urea concentration is 8．0 mol／L,the difference spectra shows a deep negative peak around 262nm；the fluorescence intensity and red shift of emission maximum continuously increased, and PLAP residual activity is 5．8％．Conclusion：The activity site of PLAP is more sensitive to urea than the molecule as a whole．

关 键 词：碱性磷酸酶 脲 变性 构象 活力 

分 类 号：Q55[生物学—生物化学]