ENERGETICS OF THE INTERACTION BETWEEN WATER, MEMBRANES AND MACROMOLECULES

水、膜和大分子之间相互作用的能量

• 批准号: 6290229
• 负责人: ALFRED L YERGEY
• 金额: --
• 依托单位: EUNICE KENNEDY SHRIVER NATIONAL INSTITUTE OF CHILD HEALTH & HUMAN DEVELOPMENT
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6290229
• 关键词: angiotensin II; electrospray ionization mass spectrometry; intermolecular interaction; macromolecule; membrane; thermodynamics; water

We have determined hydration thermodynamics, deltaH(std,298), deltaS(std,298), and deltaG(std,298), for a family of alkyl ammonium ions, CnH2n+1NH3+ for n between 1 and 8 carbons, using electrospray ionization-equilibrium gas phase ion molecule reactions at equilibrium. The hydration thermodynamic values were calculated from equilibrium constants measured under conditions of ion source water partial pressures ranging between 0 and 100 mtorr, equivalent to 0-1% of total source pressure, and ion source temperatures ranging between 5 and 65C. Equilibrium ion intensity measurements were made for at least 4 hydration states, i.e., zero through 3 water molecules associated with the core ion, at each of the 60 combinations of water partial pressures and temperatures covering the ranges of experimental variables. Results of our measurements are in close agreement with published data for some of the alkyl ammonium species for the hydration states where common data are present. Of much greater importance is that we have been able to establish for the first time a measurement of the entropic strength of a single intermolecular hydrogen bond. The values for deltaS(std) are sufficiently precise that we are able to conclude that there is an average net loss in entropy of 3 cal/deg.mole in adding the second water to an ion already having one water present, i.e., delta-deltaS(std) = 3 cal/deg.mole significant at p < 0.04. The net decrease in entropy is consistent with a gain in intermolecular ordering, that is the formation of a water - water - N+ hydrogen bond. Furthermore, our studies clearly show that 1) addition of the first water to a bare ion is apprecibly more exothermic than addition of the third; 2) addition of the first water to monoalkyl ammonium ions is about 2 kcal/mole more favorable for the case of monomethyl than for monobutyl and that there is relatively little change by further increases of alkyl chain length; 3) addition of the first water to monomethyl ammonium ions is about 3 kcal/mole more favorable for the case of trimethyl. Furthermore, addition of the first water to propyl ammonium is about 1.5 kcal/mole more favorable than the addition of the first water to trimethyl ammonium. - Thermodynamics, Hydration Enthalpy, Hydrophobicity, Equilibrium, Mass Spectrometry

我们已经确定了水合热力学，deltaH（标准差，298），deltaS（标准差，298），和deltaG（标准差，298），为一个家庭的烷基铵离子，CnH 2n +1 NH3+的n之间的1和8个碳，使用电喷雾电离平衡气相离子分子反应在平衡。水合热力学值是根据在离子源水分压范围在0至100毫托（相当于总源压力的0-1%）和离子源温度范围在5至65摄氏度之间的条件下测量的平衡常数计算的。对至少4种水合状态进行平衡离子强度测量，在覆盖实验变量范围的60种水分压和温度组合中的每一种下，与核心离子相关的0到3个水分子。我们的测量结果是在密切的协议与公布的数据为一些烷基铵物种的水合状态，其中常见的数据。更重要的是，我们已经能够建立第一次测量的熵强度的一个单一的分子间氢键。Δ S（std）的值足够精确，使得我们能够得出结论，在将第二水加入到已经存在一个水的离子中时，熵的平均净损失为3卡/度摩尔，即，Δ-Δ S（标准）= 3卡/度摩尔，p < 0.04时显著。熵的净减少与分子间有序化的增加一致，即形成水-水- N+氢键。此外，我们的研究清楚地表明，1）将第一水加入到裸离子中比加入第三水明显更放热; 2）将第一水加入到单烷基铵离子中对于单甲基比对于单丁基更有利约2kcal/mol，并且通过进一步增加烷基链长存在相对小的变化; 3）对于三甲基铵离子的情况，第一水加入到单甲基铵离子中是约3千卡/摩尔更有利。此外，向丙基铵中加入第一水比向三甲基铵中加入第一水更有利约1.5千卡/摩尔。- 热力学，水合焓，疏水性，平衡，质谱