Efficient separation of mannan–protein mixtures by ionic liquid aqueous two-phase system, comparison with lectin affinity purification

Abstract

Analysis of carbohydrates from complex biological samples often requires their isolation from proteins and other contaminants to avoid interference. An effective separation of mannan–protein mixtures by 1-butyl-3-methylimidazolium bromide/K2HPO4 ionic liquid aqueous two-phase system (IL-APTS) is reported. Extraction efficiency of bovine serum albumin (BSA) ranged from 92% to 97% while extraction efficiency of mannan reached values from 95% to about 100% depending on phase and/or model sample composition. On the contrary, lower efficiency of BSA removal (73–84%) was recorded for lectin affinity purification with concanavalin A–triazine bead cellulose (Con A-TBC); the low mannan-binding capacity was limiting factor here. The size exclusion chromatography pattern of model mannan–BSA samples after both IL-APTS and Con A-TBC treatments were consistent with the spectrophotometric component analysis. In case of biological experiment, the ionic liquid separation technique was superior in pre-purification of 2-aminobenzamide-labelled mannan from cell culture medium prior to HPLC-FLD analysis.