Dai Zhao-yun, Chu Yan-qiu, Wu Bo, Wu Liang, Ding Chuan-fan
Department of Infectious Disease, Huadong Hospital, Shanghai 200040, China.
Acta Pharmacol Sin. 2008 Jun;29(6):759-71. doi: 10.1111/j.1745-7254.2008.00791.x.
To study the non-covalent interaction between glutathione and common amino acids.
A stoichiometry of glutathione and common amino acids were mixed to reach the equilibrium, and then the mixed solution was investigated by electrospray ionization mass spectrometry (ESI-MS). The binding of the complexes was further examined by collision-induced dissociation (CID) in a tandem mass spectrometer as well as UV spectroscopy. To avoid distinct ionization efficiency discrepancy and signal suppression in the ESI-MS measurements, the interaction between glutathione (GSH) and glutamate (Glu) was quantitatively evaluated. The total concentrations and series of m/z of peak intensities for glutathione and amino acids could be achieved, respectively. Due to the existence of some oligomeric species arising from glutathione or amino acids, an improved calculation formula was proposed to calculate the dissociation constants of glutathione binding to amino acids.
The ESI mass spectra revealed that glutathione could interact easily with Met, Phe, Tyr, Ser, or Ile to form non-covalent complexes. The binding of the complexes was further confirmed by CID experiments in a tandem mass spectrometer as well as UV spectroscopy. Moreover, an improved calculation formula was successfully applied to determine the dissociation constants of glutathione binding to Glu, His, or Gln. Finally, a possible formation mechanism for the complexes of glutathione with amino acids was proposed.
The reduced polypeptide gamma-glutathione can interact with each of 8 common amino acids, including Glu, His, and Gln to form non-covalent complexes with different affinity.
研究谷胱甘肽与常见氨基酸之间的非共价相互作用。
将谷胱甘肽与常见氨基酸按化学计量比混合至达到平衡，然后用电喷雾电离质谱（ESI-MS）对混合溶液进行研究。通过串联质谱仪中的碰撞诱导解离（CID）以及紫外光谱进一步检测复合物的结合情况。为避免ESI-MS测量中明显的电离效率差异和信号抑制，对谷胱甘肽（GSH）与谷氨酸（Glu）之间的相互作用进行了定量评估。分别获得了谷胱甘肽和氨基酸的总浓度以及一系列峰强度的质荷比。由于谷胱甘肽或氨基酸会产生一些寡聚体物种，因此提出了一种改进的计算公式来计算谷胱甘肽与氨基酸结合的解离常数。
ESI质谱显示谷胱甘肽能轻易与甲硫氨酸、苯丙氨酸、酪氨酸、丝氨酸或异亮氨酸相互作用形成非共价复合物。串联质谱仪中的CID实验以及紫外光谱进一步证实了复合物的结合。此外，一种改进的计算公式成功应用于测定谷胱甘肽与谷氨酸、组氨酸或谷氨酰胺结合的解离常数。最后，提出了谷胱甘肽与氨基酸复合物可能的形成机制。
还原型多肽γ-谷胱甘肽能与包括谷氨酸、组氨酸和谷氨酰胺在内的8种常见氨基酸中的每一种相互作用，形成具有不同亲和力的非共价复合物。
