Buffer and Salt Effects in Aqueous Host-Guest Systems: Screening, Competitive Binding, or Both?
Buffer and Salt Effects in Aqueous Host-Guest Systems: Screening, Competitive Binding, or Both?
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水溶液中的缓冲液和盐效应：筛查，竞争性结合，还是两者兼而有之？
DOI：
10.1021/jacs.1c08457
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发表时间：
2021-11-10
影响因子：
15
通讯作者：
Gibb BC
中科院分区：
文献类型：
--
作者：
Jordan JH;Ashbaugh HS;Mague JT;Gibb BC
关于水中离子的超分子性质有许多悬而未决的问题，这一事实在任何涉及缓冲溶液的研究领域都有影响。事实上，正如Pielak所指出的(缓冲，特别是好的那种，生物化学，2021年，在印刷中。DOI：10.1021/acs.BioChem.1c00200)缓冲液的构思很少考虑其超分子性质。但这里有一个困难：超分子化学家用于亲和力测定的数学模型没有考虑筛选。因此，任何筛选效应的大小以及与竞争性盐/缓冲剂结合相比如何，都存在不确定性。在这里，我们使用四阳离子空穴来比较使用传统的非屏蔽模型和屏蔽(德拜-胡克尔)模型获得的卤化物亲和力。出现的经验法则是，如果离子强度变化了>；1个数量级-无论是在滴定过程中还是在两种不同的缓冲溶液之间进行比较时-应该考虑筛选。我们还建立了竞争数学模型，表明缓冲区中的结合衰减很大程度上是由于所述缓冲区与宿主的竞争结合。对于现有的系统，我们发现竞争的影响大约是筛选(25°C下的∼RT)效果的两倍。因此，对于较强的粘结剂，考虑筛选不如考虑竞争络合作用重要，但对于较弱的粘结剂，应考虑这两种影响。我们预计这些结果将有助于超分子化学家揭开缓冲液的性质，从而有助于指导生物大分子的研究。
There are many open questions regarding the supramolecular properties of ions in water, a fact that has ramifications within any field of study involving buffered solutions. Indeed, as Pielak has noted (Buffers, Especially the Good Kind, Biochemistry, 2021, in press. DOI:10.1021/acs.biochem.1c00200) buffers were conceived of with little regard to their supramolecular properties. But there is a difficulty here; the mathematical models supramolecular chemists use for affinity determinations do not account for screening. As a result, there is uncertainty as to the magnitude of any screening effect and how this compares to competitive salt/buffer binding. Here we use a tetra-cation cavitand to compare halide affinities obtained using a traditional unscreened model and a screened (Debye–Hückel) model. The rule of thumb that emerges is that if ionic strength is changed by >1 order of magnitude—either during a titration or if a comparison is sought between two different buffered solutions—screening should be considered. We also build a competitive mathematical model showing that binding attenuation in buffer is largely due to competitive binding to the host by said buffer. For the system at hand, we find that the effect of competition is approximately twice that of the effect of screening (∼RT at 25 °C). Thus, for strong binders it is less important to account for screening than it is to account for competitive complexation, but for weaker binders both effects should be considered. We anticipate these results will help supramolecular chemists unravel the properties of buffers and so help guide studies of biomacromolecules.
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影响因子：
2.9
作者：
GOOD, NE;WINGET, GD;SINGH, RMM
通讯作者：
SINGH, RMM
影响因子：
2.9
作者：
Pielak, Gary J.
通讯作者：
Pielak, Gary J.
影响因子：
3.3
作者：
Chan, Ching W.;Smith, David K.
通讯作者：
Smith, David K.
影响因子：
15
作者：
Jordan, Jacobs H.;Gibb, Corinne L. D.;Wishard, Anthony;Thu Pham;Gibb, Bruce C.
通讯作者：
Gibb, Bruce C.
影响因子：
16.6
作者：
Kostiainen, MA;Hardy, JG;Smith, DK
通讯作者：
Smith, DK