Khan Parvez, Parkash Amresh, Islam Asimul, Ahmad Faizan, Hassan Md Imtaiyaz
Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, 110025, India.
Biopolymers. 2016 Mar;105(3):133-42. doi: 10.1002/bip.22760.
Hemochromatosis factor E (HFE) is a member of class I MHC family and plays a significant role in the iron homeostasis. Denaturation of HFE induced by guanidinium chloride (GdmCl) was measured by monitoring changes in [θ]222 (mean residue ellipticity at 222 nm), intrinsic fluorescence emission intensity at 346 nm (F346 ) and the difference absorption coefficient at 287 nm (Δε287) at pH 8.0 and 25°C. Coincidence of denaturation curves of these optical properties suggests that GdmCl-induced denaturation (native (N) state ↔ denatured (D) state) is a two-state process. The GdmCl-induced denaturation was found reversible in the entire concentration range of the denaturant. All denaturation curves were analyzed for ΔGD0, Gibbs free energy change associated with the denaturation equilibrium (N state ↔ D state) in the absence of GdmCl, which is a measure of HFE stability. We further performed molecular dynamics simulation for 40 ns to see the effect of GdmCl on the structural stability of HFE. A well defined correlation was established between in vitro and in silico studies.
血色素沉着症因子E（HFE）是I类主要组织相容性复合体（MHC）家族的成员，在铁稳态中发挥重要作用。通过监测在pH 8.0和25°C下222nm处的[θ]222（平均残基椭圆率）、346nm处的固有荧光发射强度（F346）以及287nm处的差异吸收系数（Δε287）的变化，来测定由氯化胍（GdmCl）诱导的HFE变性。这些光学性质的变性曲线的重合表明，GdmCl诱导的变性（天然（N）状态↔变性（D）状态）是一个两态过程。发现在变性剂的整个浓度范围内，GdmCl诱导的变性是可逆的。分析所有变性曲线的ΔGD0，即与在无GdmCl时变性平衡（N状态↔D状态）相关的吉布斯自由能变化，它是HFE稳定性的一种度量。我们进一步进行了40纳秒的分子动力学模拟，以观察GdmCl对HFE结构稳定性的影响。在体外和计算机模拟研究之间建立了明确的相关性。
