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首页> 外文期刊>Journal of chromatography, A: Including electrophoresis and other separation methods >Enantioselective retention mechanisms of dipeptides on antibiotic-based chiral stationary phases: Leucyl-leucine, glycyl-leucine, and leucyl-glycine as case studies
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Enantioselective retention mechanisms of dipeptides on antibiotic-based chiral stationary phases: Leucyl-leucine, glycyl-leucine, and leucyl-glycine as case studies

机译：基于抗生素的手性固定阶段的二肽的映选择性保留机制：白胶亮氨酸，甘糖苷和白甘糖基 - 甘氨酸作为案例研究

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Chromatographic behaviors of dipeptides consisting of leucine and glycine were studied on two antibiotic-based chiral stationary phases (CSPs) with teicoplanin (Chirobiotic T) or ristocetin A (Chirobiotic R) as chiral selectors under reversed-phase conditions. The effect of mobile phase pH on the retention of stereoisomers of dipeptides was investigated and thermodynamic characteristic of adsorption were measured at different pH values. It was shown that the retention of dipeptides depends on the ionization of their molecules in the mobile phase, as different ionic forms have different affinity towards antibiotic selectors. Enantioselectivity of the bound antibiotics with respect to Leu-Leu stereoisomers was achieved via steric modulation of ion-ion interactions between the solute and the selector, while in the case of Gly-Leu enantiomers non-ionic interactions such as hydrogen bonding might play the key role. In both cases, the dipeptides terminating in D-Leu were retained stronger than their optical antipodes, whereas the enantiomers of Leu-Gly were hardly separated. The regression analysis of the retention data applying the Horvath-Melander-Molnar model revealed that different types of enantioselectivity resides in particular ionic forms of the compounds: cations are responsible for the separation of diastereomeric pairs and the anionic and zwitterionic forms have a universal enantioselectivity on the Chirobiotic T CSP, and the anions and zwitterions are the enantioselective forms for the Chirobiotic R CSP. (C) 2019 Elsevier B.V. All rights reserved.
机译：在两种抗生素的手性固定阶段（CSP）上用辛丙氨酸（Chirobiotic T）或ristocetina（Chirobiotic R）在反相条件下作为手性选择器进行色谱行为。研究了流动相pH对偶氮二肽立体异构体保持的影响，并在不同的pH值下测量吸附的热力学特性。结果表明，二肽的保留取决于其在流动相中分子的电离，因为不同的离子形式对抗生素选择器具有不同的亲和力。通过溶质和选择器之间的离子离子相互作用的空间调制实现结合抗生素对Leu-Leu立体异构体的对映选择性，而在Gly-Leu对映异构体的情况下，诸如氢键的非离子相互作用可能发挥钥匙角色。在这两种情况下，在d-LEU终止二肽比其旋光对映体保留了更强，而亮氨酸 - 甘氨酸的对映异构体难以分离。应用Horvath-Melander-Molnar模型的保留数据的回归分析显示，不同类型的对映选择性尤其存在于化合物的离子形式：阳离子负责分离非对映异构体对，并且阴离子和两性离子形式对普通对映射性具有通向ChiroBiotic T CSP和阴离子和两性是脊椎生物r CSP的对映选择性形式。 （c）2019 Elsevier B.v.保留所有权利。

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