Analysis of isolectins on non-porous particles and monolithic polystyrene-divinylbenzene based stationary phases and electrospray ionization mass spectrometry

This paper reports on the use of non-porous particular octadecylated and monolithic polystyrene-divinylbenzene (PS-DVB) based stationary phases coupled to mass spectrometry (MS) for the fast separation and characterization of important plant isolectins. Optimization of the mobile phase allowed the analysis of a mixture consisting of lentil, wheat germ lectins and concanavalin A within 10 min using both column technologies. The monolithic PS-DVB phase showed higher efficiency for the separation of the wheat germ lectin isoforms and the concanavalin A proteolytic fragments. Using UV-detection at 214 nm multiple peaks were observed corresponding to fragments or isoforms of each individual lectin. Due to the higher efficiency and the lower flow rate (3 muL/min) the monolithic capillary column was coupled to mass spectrometry (MS) via an electrospray ionization (ESI) interface. MS detection allowed the selective identification of three wheat germ and two lentil isolectins. In case of concanavalin A two proteolytic fragments were identified, which are generated during post-translational processing of the protein. Finally, the established LC-ESI-MS method was used for the identification of the lentil isolectin in a complex lentil extract. (Int J Mass Spectrom 223-224 (2003) 519-526) (C) 2002 Elsevier Science B.V. All rights reserved.