title: Enthalpy contributions to adsorption of highly charged lysozyme onto a cation-exchanger under linear and overloaded conditions.
abstract: An investigation of the adsorption mechanism of lysozyme onto carboxymethyl cellulose (CMC) was conducted using flow calorimetry and adsorption isotherm measurements. This study was undertaken to provide additional insight into the underlying mechanisms involved in protein adsorption that traditional approaches such isotherm measurements or van't Hoff analysis can't always provide, particularly when protein adsorption occurs under overloaded conditions. Lysozyme and CMC were selected for this study because the characteristics of the protein and the adsorbent are well known, hence, allowing the focus of this work to be on the driving forces influencing adsorption. Calorimetry results have showed that lysozyme adsorption onto CMC produced both exothermic and endothermic heats of adsorption. More specifically flow calorimetry data coupled with peak deconvolution methods illustrated a series of chronological events that included dilution, primary protein adsorption, rearrangement of surface proteins and a secondary adsorption of lysozyme molecules. The observations and conclusions derived from the experimental work presented in our figures and tables were developed within the mechanistic framework proposed by Lin et al., J. Chromatogr. A. 912 (2001) 281.
authors.affiliation: CICS-UBI-Health Sciences Research Centre, University of Beira Interior, 6200-506 Covilhã, Portugal; Department of Chemistry, University of Beira Interior, 6201-001 Covilhã, Portugal.
authors.forename: G L
authors.initials: GL
authors.lastname: Silva
authors.affiliation: CICS-UBI-Health Sciences Research Centre, University of Beira Interior, 6200-506 Covilhã, Portugal; Department of Chemistry, University of Beira Interior, 6201-001 Covilhã, Portugal.
authors.forename: F S
authors.initials: FS
authors.lastname: Marques
authors.affiliation: Department of Water Resources and Environmental Engineering, College of Science and Engineering, Central State University, Wilberforce, OH, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Thrash
authors.affiliation: CICS-UBI-Health Sciences Research Centre, University of Beira Interior, 6200-506 Covilhã, Portugal; Department of Chemistry, University of Beira Interior, 6201-001 Covilhã, Portugal. Electronic address: ccabral@fcsaude.ubi.pt.
authors.forename: A C
authors.initials: AC
authors.lastname: Dias-Cabral
mesh_terms: D000327:Adsorption; D002151:Calorimetry; D002411:Cation Exchange Resins / Q000737:chemistry*; D002412:Cations; D009113:Muramidase / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D002411:Cation Exchange Resins; D002412:Cations; D009113:Muramidase
keywords: Adsorption isotherms; Carboxymethyl cellulose; Flow microcalorimetry; Ion-exchange chromatography; Lysozyme