Investigation of the adsorption behavior of glycine peptides on 12% cross-linked agarose gel media |
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Authors: | Xiaoou Zhang Jörgen Samuelsson Jan-Christer Janson Changhai Wang Zhiguo Su Ming Gu Torgny Fornstedt |
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Institution: | 1. Department of Biological Science and Technology, School of Environmental and Biological Science and Technology, Dalian University of Technology, Dalian, 116024, China;2. Department of Physical and Analytical Chemistry, Uppsala Biomedical Centre, Uppsala University, Box 599, SE-751 24 Uppsala, Sweden;3. National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Box 353, Beijing, 100190, China |
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Abstract: | The highly cross-linked 12% agarose gel Superose 12 10/300 GL causes retardation of glycine peptides when mobile phases containing varying concentrations of acetonitrile in water are used. An investigation has been made into the retention mechanism behind this retardation using the glycine dipeptide (GG) and tripeptide (GGG) as models. The dependence of retention times of analytical-size peaks under different experimental conditions was interpreted such that the adsorption most probably was caused by the formation of hydrogen bonds but that electrostatic interactions cannot be ruled out. Thereafter, a nonlinear adsorption study was undertaken at different acetonitrile content in the eluent, using the elution by characteristic points (ECPs) method on strongly overloaded GG and GGG peaks. With a new evaluation tool, the adsorption energy distribution (AED) could be calculated prior to the model selection. These calculations revealed that when the acetonitrile content in the eluent was varied from 0% to 20% the interactions turned from (i) being homogenous (GG) or mildly heterogeneous (GGG), (ii) via a more or less stronger degree of heterogeneity around one site to (iii) finally a typical bimodal energy interaction comprising of two sites (GG at 20% and GGG at 10% and 20%). The Langmuir, Tóth and bi-Langmuir models described these interesting adsorption trends excellently. Thus, the retardation observed for these glycine peptides is interpreted as being of mixed-mode character composed of electrostatic bonds and hydrogen bonds. |
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Keywords: | Superose 12 10/300 GL Peptides Adsorption isotherms Adsorption energy distribution Heterogeneous interaction Hydrogen bond formation Langmuir model Tó th model bi-Langmuir model Mixed mode Electrostatic interactions |
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