ABSTRACT
I. INTRODUCTION It has been recognized recently that interactions between proteins and car bohydrate chains play important cell biological roles, particularly in cell cell interactions and the signal transduction mechanisms. For example, noncovalent binding of cholera toxin B-subunit (CTB) with the ligand GM la is well recognized [1-4]. Although there are now several methods to analyze such complexes, we investigated the use of electrospray ionization mass spectrometry (ESI/MS) [5] to determine the specificity and stoichi ometry of CTB binding. Being an MS method that does not produce frag mentation unless skimmer voltage is applied, ESI/MS has been used to measure the mass of intact proteins and common glycolipids, such as the tetrasialoganglioside GQlb [6] and polysulfated Le-type glycoconjugates [7,8]. ESI/MS is also one of the two methods currently available for ana lyzing proteins that may play important roles when complexed with sugar chains.
