Transitional metal ions widely exist in biological environments and are crucial to many life-sustaining physiological processes. Recently, transition metal ion such as Cu2+, Zn2+, Ni2+, have been shown can increase the solubilities of aromatic biomolecules. Comparing with Cu2+, Zn2+ shows less enhancement to the solubilities of biomolecules such as tryptophan (Trp). On the other hand, Zn2+ has a higher concentration in human blood plasma and appears in protein the most among transition metal ions, clarifying whether Zn2+ can enhance the solubilities of other aromatic amino acids is significantly important. Herein, we observed that the solubility of aromatic amino acid histidine (His) is greatly enhanced in ZnCl2 solution. Based on first principle calculations, this enhancement of solubility is attributed to cation-π interaction between His and Zn2+. Our results here are of great importance for the bioavailability of aromatic drugs and provide new insights for the understanding of physiological functions of Zn2+.
@article{arxiv.2004.03798,
title = {Enhanced water affinity of histidine by transition metal ions},
author = {Yongshun Song and Jing Zhan and Minyue Li and Hongwei Zhao and Guosheng Shi and Minghong Wu and Haiping Fang},
journal= {arXiv preprint arXiv:2004.03798},
year = {2020}
}