Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia 142290.
J Phys Chem B. 2012 May 24;116(20):5872-81. doi: 10.1021/jp300370r. Epub 2012 May 14.
The process of neutralizing hydrated multicharged gas-phase protein ions with small counterions was simulated using a molecular dynamics (MD) technique. Hen egg white lysozyme (HEWL) molecules with different numbers of positive charges, both dry and solvated by up to 1500 water molecules, were first equilibrated. Simulations revealed that the hydration layer over a highly charged protein surface adapted a spiny structure with water protrusions composed of oriented water dipoles. MD simulations of the neutralization process showed that the impact of a small dehydrated single-charged counterion with a dehydrated HEWL ion bearing eight uncompensated charges resulted in a short local increase in temperature by 600-1000 K, which quickly (in 3-5 ps) dissipated over the whole protein molecule, increasing its average temperature by 20-25 K. When the protein ion was solvated, no drastic local increase in the temperature of the protein atoms was observed, because the impact energy was dissipated among the water molecules near the collision site.
采用分子动力学（MD）技术模拟了带小反离子的水合多电荷气相蛋白离子的中和过程。首先平衡了具有不同正电荷数的干态和溶剂化至多达 1500 个水分子的鸡卵清溶菌酶（HEWL）分子。模拟表明，带高电荷的蛋白质表面的水合层适应了一种刺状结构，其中包含由取向水分子偶极子组成的水突起。中和过程的 MD 模拟表明，一个脱水的带单电荷的反离子与一个带有八个未补偿电荷的脱水 HEWL 离子的碰撞导致局部温度短时间内升高 600-1000 K，该温度在 3-5 ps 内迅速耗散到整个蛋白质分子，使蛋白质分子的平均温度升高 20-25 K。当蛋白质离子被溶剂化时，没有观察到蛋白质原子的局部温度急剧升高，因为碰撞部位附近水分子之间的冲击能量耗散了。
