酸诱导拥挤条件下肌红蛋白及突变体去折叠过程  

Acid-Induced Unfolding Process of Myoglobin and Its Mutant under Macromolecular Crowding Conditions

作　　者：张玉姣[1] 唐乾[1] 曹洪玉[1] 郑学仿[1,2] 

机构地区：[1]大连大学生命科学与技术学院,辽宁大连116622 [2]大连大学辽宁省生物有机化学重点实验室,辽宁大连116622

出　　处：《物理化学学报》2013年第8期1785-1792,共8页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(21271036;20871024)资助项目~~

摘　　要：采用紫外-可见吸收光谱、同步荧光光谱和圆二色(CD)光谱法研究拥挤试剂葡聚糖70(Dextran70)和聚蔗糖70(Ficoll70)存在条件下,酸诱导野生型肌红蛋白Mb(WT)及其突变体Mb(D60K)的去折叠过程.结果显示:在Dextran70和Ficoll70两种拥挤环境下,Mb(WT)的变性中点pH值由4.25分别降低到3.78与3.76,拥挤试剂加入后增强了Mb(WT)的耐酸能力;肌红蛋白60位天冬氨酸(Asp)突变为赖氨酸(Lys)后,变性中点pH值由4.25降低到4.19,耐酸性比野生型肌红蛋白有所增强,Mb(D60K)在Dextran70和Ficoll70两种拥挤环境下变性中点pH值由4.19分别降至3.74和3.12.以上实验说明肌红蛋白表面氨基酸突变和拥挤试剂的添加起到了稳定血红素微环境、芳香族氨基酸及二级结构和保护蛋白天然状态的作用.In this paper, we studied the unfolding process of myoglobin （Mb） and its mutant Mb（D60K） induced by acid under macromolecular crowding conditions, using ultraviolet-visible absorption, synchronous fluorescence, and circular dichroism （CD） spectroscopies. The spectroscopic data showed that, with the addition of Dextran70 or Ficoll70, the denaturation midpoint of Mb（WT） decreased from 4.25 to 3.78 or 3.76, respectively. In addition, the acid tolerance of Mb（WT） improved under macromolecular crowding conditions. The denaturation midpoint of Mb（D60K） was 4.19, which was a slight decrease from that of Mb （4.25）. Upon addition of Dextran70 or Ficoll70, the denaturation midpoint of Mb（D60K） decreased from 4.19 to 3.74 or 3.12, respectively. The spectroscopic results illustrated that the amino acid mutant and crowding agents could stabilize the microenvironment surrounding the heme and aromatic amino acid as well as the second structure of Mb, protecting its native state.

关 键 词：拥挤试剂 酸变性 肌红蛋白 突变体 光谱法 

分 类 号：Q51[生物学—生物化学]