Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi 110025, India.
Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi 110025, India.
Int J Biol Macromol. 2019 Apr 1;126:488-495. doi: 10.1016/j.ijbiomac.2018.12.183. Epub 2018 Dec 23.
Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), is an obligate pathogen that causes 10.4 million new infections worldwide, out of which about 1.4 million die every year. SDS is routinely used to mimic the native hydrophobic environment of phospholipid bilayer. Here, we report structure and stability of a mammalian cell entry protein from M. tuberculosis (Mce4A) in the absence and presence of SDS. The far-UV circular dichroism (CD) measurements suggested that SDS induces α-helical structure in Mce4A. Stability of the protein in the absence and presence of SDS was measured from the analysis of the urea-induced denaturation curves of three physical properties (CD, intrinsic fluorescence and near-UV absorption). These measurements led to the conclusion that SDS stabilizes Mce4A. Binding of SDS with Mce4A was measured in isothermal titration calorimeter, which led to the conclusion that there is strong binding of SDS with Mce4A. We propose that the membrane associated Mce4A is more structured and more stable.
结核分枝杆菌（Mycobacterium tuberculosis）是引起结核病（TB）的病原体，是一种专性病原体，在全球范围内导致 1040 万例新感染，其中每年约有 140 万人死亡。SDS 通常用于模拟磷脂双层的天然疏水环境。在这里，我们报告了结核分枝杆菌（M. tuberculosis）的一种哺乳动物细胞进入蛋白（Mce4A）在没有和存在 SDS 时的结构和稳定性。远紫外圆二色性（CD）测量表明 SDS 诱导 Mce4A 形成α-螺旋结构。通过分析三种物理性质（CD、内源荧光和近紫外吸收）的尿素诱导变性曲线，测量了 SDS 存在和不存在时蛋白质的稳定性。这些测量得出的结论是 SDS 稳定了 Mce4A。在等温滴定量热仪中测量了 SDS 与 Mce4A 的结合，得出的结论是 SDS 与 Mce4A 有很强的结合。我们提出与膜相关的 Mce4A 更具结构和更稳定。
