title: Investigation of the adsorption behavior of glycine peptides on 12% cross-linked agarose gel media.
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.
authors.affiliation: Department of Biological Science and Technology, School of Environmental and Biological Science and Technology, Dalian University of Technology, Dalian, 116024, China.
authors.forename: Xiaoou
authors.initials: X
authors.lastname: Zhang
authors.forename: Jörgen
authors.initials: J
authors.lastname: Samuelsson
authors.forename: Jan-Christer
authors.initials: JC
authors.lastname: Janson
authors.forename: Changhai
authors.initials: C
authors.lastname: Wang
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Su
authors.forename: Ming
authors.initials: M
authors.lastname: Gu
authors.forename: Torgny
authors.initials: T
authors.lastname: Fornstedt
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D000327:Adsorption; D002021:Buffers; D002845:Chromatography; D003432:Cross-Linking Reagents / Q000737:chemistry*; D019277:Entropy; D005782:Gels; D005998:Glycine / Q000302:isolation & purification*; D006033:Glycylglycine / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D010455:Peptides / Q000302:isolation & purification*; D012685:Sepharose / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D000097:Acetonitriles; D002021:Buffers; D003432:Cross-Linking Reagents; D005782:Gels; D010455:Peptides; D014867:Water; D006033:Glycylglycine; D012965:Sodium Chloride; D012685:Sepharose; D005998:Glycine; C032159:acetonitrile