Effect of Transition-Metal Ions on the Conformation of Encephalin Investigated by Hydrogen/Deuterium Exchange and Theoretical Calculations.,The Journal of Physical Chemistry B

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Effect of Transition-Metal Ions on the Conformation of Encephalin Investigated by Hydrogen/Deuterium Exchange and Theoretical Calculations.
The Journal of Physical Chemistry B ( IF 2.8 ) Pub Date : 2019-12-30 , DOI: 10.1021/acs.jpcb.9b09919
Fangling Wu ₁ , Yandong Huang ₂ , Fanzhen Yu ₂ , Zhenhua Li ₂ , Chuan-Fan Ding ₁

Affiliation

We have studied the effects of different 3d orbitals in divalent transition-metal ions [G2+ = Mn2+ (d5), Fe2+ (d6), Co2+ (d7), Ni2+ (d8), Cu2+ (d9), or Zn2+ (d10)] on the conformations of leucine encephalin (LE) and methionine encephalin (ME) in the gas phase using hydrogen/deuterium exchange mass spectrometry (HDX-MS) and theoretical calculations at the molecular level. The HDX-MS reveals a 1:1 stoichiometric monovalent complex of [LE/ME + G - H]+ and observed that the different HDX reactivities follow the trend Fe2+ < Co2+ < Ni2+ < Mn2+ < Cu2+ ≈ Zn2+ and that [ME + Mn/Cu/Zn - H]+ > [LE + Mn/Cu/Zn - H]+, while [LE + Fe/Co/Ni - H]+ > [ME + Fe/Co/Ni - H]+. We cross-correlated the collision-induced dissociation energies of the complexes with the HDX results and found that the more stable the complex, the harder it is for it to undergo HDX. Furthermore, we used theoretical calculations to optimize the favorable conformations of the complexes and found the same interaction structure of G2+ coordination with the five carbonyl oxygens of LE/ME that have different bond lengths. Finally, we calculated the proton affinity (PA) values of the optimized complexes in order to interpret the HDX observations that the higher the PA values, the more difficult it is for the complex to undergo HDX. Overall, both the experiments and the theoretical calculations show that the six metal ions have different effects on the LE/ME conformation, with the low-energy stability of the G2+ 3d orbitals corresponding to more dramatic effects on the LE/ME conformation. In addition, the hardness of the ionic acid corresponding to the fully filled Mn2+ and half-filled Zn2+ orbitals also contributes strongly to the coordination effect; the conformation effect of Fe2+/Co2+/Ni2+ on LE is greater than that on ME, whereas the conformation effect of Mn2+/Cu2+/Zn2+ on ME is greater than that on LE.

中文翻译：

氢/氘交换法研究过渡金属离子对脑啡肽构象的影响及理论计算。

我们研究了不同3d轨道对二价过渡金属离子[G2 + = Mn2 +（d5），Fe2 +（d6），Co2 +（d7），Ni2 +（d8），Cu2 +（d9）或Zn2 +（d10）的影响）。氢/氘交换质谱法（HDX-MS）在气相中对亮氨酸脑素（LE）和蛋氨酸脑素（ME）进行构象，并在分子水平上进行理论计算。HDX-MS揭示了[LE / ME + G-H] +的1：1化学计量单价络合物，并观察到不同的HDX反应性遵循Fe2 + <Co2 + <Ni2 + <Mn2 + <Cu2 +≈Zn2 +趋势，以及[ME + Mn / Cu / Zn-H] +> [LE + Mn / Cu / Zn-H] +，而[LE + Fe / Co / Ni-H] +> [ME + Fe / Co / Ni-H] +。我们将配合物的碰撞诱导解离能与HDX结果进行了互相关，发现配合物越稳定，HDX越难。此外，我们使用理论计算来优化配合物的有利构象，并发现G2 +与LE / ME的五个羰基氧具有不同键长的配位结构相同。最后，我们计算了优化复合物的质子亲和力（PA）值，以解释HDX观察结果，即PA值越高，复合物经历HDX的难度就越大。总体而言，实验和理论计算均表明六种金属离子对LE / ME构象具有不同的影响，G2 + 3d轨道的低能量稳定性对应于对LE / ME构象的更剧烈的影响。此外，Mn2 +完全填充和Zn2 +完全填充的离子酸的硬度也对配位作用有很大的贡献。Fe2 + / Co2 + / Ni2 +对LE的构象作用大于对ME的构象作用，而Mn2 + / Cu2 + / Zn2 +对ME的构象作用大于对LE的构象作用。

更新日期：2019-12-30

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