Department of Pharmaceutical Chemistry, Comenius University, Odbojarov 10, 832 32, Bratislava, Slovakia.
Amino Acids. 2010 Nov;39(5):1309-19. doi: 10.1007/s00726-010-0573-8. Epub 2010 Apr 3.
Interactions between metal ions and amino acids are common both in solution and in the gas phase. The effect of metal ions and water on the structure of L-histidine is examined. The effect of metal ions (Li+, Na+, K+, Mg2+, Ca2+, Ni2+, Cu2+ and Zn2+) and water on structures of His·M(H2O)m, m=0.1 complexes have been determined theoretically employing density functional theories using extended basis sets. Of the five stable complexes investigated the relative stability of the gas-phase complexes computed with DFT methods (with one exception of K+ systems) suggest metallic complexes of the neutral L-histidine to be the most stable species. The calculations of monohydrated systems show that even one water molecule has a profound effect on the relative stability of individual complexes. Proton dissociation enthalpies and Gibbs energies of L-histidine in the presence of the metal cations Li+, Na+, K+, Mg2+, Ca2+, Ni2+, Cu2+ and Zn2+ were also computed. Its gas-phase acidity considerably increases upon chelation. Of the Lewis acids investigated, the strongest affinity to L-histidine is exhibited by the Cu2+ cation. The computed Gibbs energies ΔG are negative, span a rather broad energy interval (from -130 to -1,300 kJ/mol), and upon hydration are appreciably lowered.
金属离子与氨基酸之间的相互作用在溶液中和气相中都很常见。本文研究了金属离子和水对 L-组氨酸结构的影响。采用扩展基组，运用密度泛函理论，从理论上确定了金属离子（Li+、Na+、K+、Mg2+、Ca2+、Ni2+、Cu2+和 Zn2+）和水对 His·M（H2O）m（m=0.1）配合物结构的影响。在所研究的五个稳定配合物中，DFT 方法计算的气相配合物的相对稳定性（除了 K+体系的一个例外）表明，中性 L-组氨酸的金属配合物是最稳定的物种。一水化体系的计算表明，即使只有一个水分子也会对各个配合物的相对稳定性产生深远影响。还计算了金属阳离子 Li+、Na+、K+、Mg2+、Ca2+、Ni2+、Cu2+和 Zn2+存在下 L-组氨酸的质子离解焓和吉布斯自由能。其气相酸度在螯合后大大增加。在所研究的路易斯酸中，Cu2+阳离子对 L-组氨酸的亲和力最强。计算得到的 Gibbs 自由能ΔG 为负值，跨越相当宽的能量间隔（从-130 到-1300 kJ/mol），并且在水合后会显著降低。
